diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0ea045088fe..66f85ea5601 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -179,6 +179,14 @@ jobs:
         run: git diff --exit-code lib/js lib/es6
         working-directory: packages/@rescript/runtime
 
+      - name: Build @rescript/belt
+        run: yarn workspace @rescript/belt build
+        shell: bash
+
+      - name: Check for changes in @rescript/belt/lib
+        run: git diff --exit-code lib/js lib/es6
+        working-directory: packages/@rescript/belt
+
       - name: Version Check
         run: yarn constraints
 
@@ -401,7 +409,7 @@ jobs:
       - name: Publish packages to pkg.pr.new
         id: publish
         run: |
-          yarn dlx pkg-pr-new publish "." "./packages/@rescript/*"
+          yarn dlx pkg-pr-new publish --yarn "." "./packages/@rescript/*"
 
   api-docs:
     needs:
@@ -493,12 +501,24 @@ jobs:
         run: |
           COMMIT_SHA="${{ needs.pkg-pr-new.outputs.commit_sha }}"
           npm i --no-audit \
-            "https://pkg.pr.new/rescript-lang/rescript@${COMMIT_SHA}"
+            "https://pkg.pr.new/rescript-lang/rescript@${COMMIT_SHA}" \
+            "https://pkg.pr.new/rescript-lang/rescript/@rescript/runtime@${COMMIT_SHA}" \
+            "https://pkg.pr.new/rescript-lang/rescript/@rescript/belt@${COMMIT_SHA}"
         shell: bash
         working-directory: ${{ steps.tmp-dir.outputs.path }}
 
       - name: Test installation
-        run: npx rescript -h && npx rescript build && cat src/Test.res.js
+        run: |
+          npx rescript -h
+          npx rescript build
+          cp src/BeltTest.res.txt src/BeltTest.res
+          if npx rescript build; then
+            echo "Belt unexpectedly compiled without being listed as a dependency" >&2
+            exit 1
+          fi
+          cp rescript-with-belt.json rescript.json
+          npx rescript build
+          node src/BeltTest.mjs
         shell: bash
         working-directory: ${{ steps.tmp-dir.outputs.path }}
 
@@ -548,12 +568,24 @@ jobs:
           COMMIT_SHA="${{ needs.pkg-pr-new.outputs.commit_sha }}"
           # pnpm 10 blocks pkg.pr.new's URL-based platform subdependencies unless block-exotic-subdeps is disabled.
           pnpm --config.block-exotic-subdeps=false i \
-            "https://pkg.pr.new/rescript-lang/rescript@${COMMIT_SHA}"
+            "https://pkg.pr.new/rescript-lang/rescript@${COMMIT_SHA}" \
+            "https://pkg.pr.new/rescript-lang/rescript/@rescript/runtime@${COMMIT_SHA}" \
+            "https://pkg.pr.new/rescript-lang/rescript/@rescript/belt@${COMMIT_SHA}"
         shell: bash
         working-directory: ${{ steps.tmp-dir.outputs.path }}
 
       - name: Test installation
-        run: pnpm rescript -h && pnpm rescript build && cat src/Test.res.js
+        run: |
+          pnpm rescript -h
+          pnpm rescript build
+          cp src/BeltTest.res.txt src/BeltTest.res
+          if pnpm rescript build; then
+            echo "Belt unexpectedly compiled without being listed as a dependency" >&2
+            exit 1
+          fi
+          cp rescript-with-belt.json rescript.json
+          pnpm rescript build
+          node src/BeltTest.mjs
         shell: bash
         working-directory: ${{ steps.tmp-dir.outputs.path }}
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e29f818a89e..3e6e87c7660 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
 #### :boom: Breaking Change
 
 - Remove the deprecated `Js` namespace and its runtime modules. https://github.com/rescript-lang/rescript/pull/8531
+- Move Belt into the separately installed `@rescript/belt` package. Projects using Belt must install the package and list it in their `rescript.json` dependencies. https://github.com/rescript-lang/rescript/pull/8554
 
 #### :eyeglasses: Spec Compliance
 
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 46078febc0b..eb9b33f116b 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -147,7 +147,7 @@ make checkformat
 
 ## Adding new Files to the Npm Packages
 
-To make sure that no files are added to or removed from the `rescript` or `@rescript/runtime` npm package inadvertently, an artifact list is kept at `packages/artifacts.json`. During CI build, it is verified that only the files that are listed there are actually included in the npm packages.
+To make sure that no files are added to or removed from the `rescript`, `@rescript/runtime`, or `@rescript/belt` npm package inadvertently, an artifact list is kept at `packages/artifacts.json`. During CI build, it is verified that only the files that are listed there are actually included in the npm packages.
 
 After adding a new file to the repository that should go into one of the npm packages - e.g., a new stdlib module -, run `make artifacts`.
 
@@ -325,7 +325,8 @@ Note that building the cmijs is based on the dependencies defined in `packages/p
 After a successful compilation, you will find following files in your project:
 
 - `packages/playground/compiler.js` -> This is the ReScript compiler, which binds the ReScript API to the `window` object.
-- `packages/playground/packages/compiler-builtins` -> The compiler base cmij containing all the relevant core modules (`Js`, `Belt`, `Pervasives`, etc.)
+- `packages/playground/packages/compiler-builtins` -> The compiler base cmij containing the runtime and standard-library modules
+- `packages/playground/packages/@rescript/belt` -> The Belt cmij, packaged separately from the compiler built-ins
 - `packages/playground/packages/*` -> Contains third party deps with cmij.js files (as defined in `packages/playground/rescript.json`)
 
 You can now use the `compiler.js` file either directly by using a `<script src="/path/to/compiler.js"/>` and `<script src="/path/to/packages/compilerCmij.js"/>` inside a html file, use a browser bundler infrastructure to optimize it, or use `nodejs` to run it on a command line:
diff --git a/Makefile b/Makefile
index bec611f7661..5d4999d8da8 100644
--- a/Makefile
+++ b/Makefile
@@ -41,6 +41,7 @@ endef
 
 BIN_DIR := packages/@rescript/$(RESCRIPT_PLATFORM)/bin
 RUNTIME_DIR := packages/@rescript/runtime
+BELT_DIR := packages/@rescript/belt
 DUNE_BIN_DIR = ./_build/install/default/bin
 
 # Build stamps
@@ -56,6 +57,8 @@ COMPILER_BUILD_STAMP := _build/log
 # after running `yarn workspace @rescript/runtime build`, which now runs `touch`
 # as part of its build script.
 RUNTIME_BUILD_STAMP := packages/@rescript/runtime/.buildstamp
+# Belt workspace touches this stamp after building against the runtime.
+BELT_BUILD_STAMP := packages/@rescript/belt/.buildstamp
 
 # Default target
 
@@ -127,15 +130,20 @@ clean-compiler:
 # Runtime / stdlib
 
 RUNTIME_SOURCES := $(shell find $(RUNTIME_DIR) -path '$(RUNTIME_DIR)/lib' -prune -o -type f \( -name '*.res' -o -name '*.resi' -o -name 'rescript.json' \) -print)
+BELT_SOURCES := $(shell find $(BELT_DIR) -path '$(BELT_DIR)/lib' -prune -o -type f \( -name '*.res' -o -name '*.resi' -o -name 'rescript.json' \) -print)
 
-lib: $(RUNTIME_BUILD_STAMP)
+lib: $(RUNTIME_BUILD_STAMP) $(BELT_BUILD_STAMP)
 
 $(RUNTIME_BUILD_STAMP): $(RUNTIME_SOURCES) $(COMPILER_EXES) $(RESCRIPT_EXE) | $(YARN_INSTALL_STAMP)
 	yarn workspace @rescript/runtime build
 
+$(BELT_BUILD_STAMP): $(BELT_SOURCES) $(RUNTIME_BUILD_STAMP) $(COMPILER_EXES) $(RESCRIPT_EXE) | $(YARN_INSTALL_STAMP)
+	yarn workspace @rescript/belt build
+
 clean-lib:
+	yarn workspace @rescript/belt rescript clean
 	yarn workspace @rescript/runtime rescript clean
-	rm -f $(RUNTIME_BUILD_STAMP)
+	rm -f $(RUNTIME_BUILD_STAMP) $(BELT_BUILD_STAMP)
 
 # Artifact list
 
@@ -198,7 +206,7 @@ $(PLAYGROUND_BUILD_STAMP): $(COMPILER_SOURCES)
 # Creates all the relevant core and third party cmij files to side-load together with the playground bundle
 playground-cmijs: $(PLAYGROUND_CMI_BUILD_STAMP)
 
-$(PLAYGROUND_CMI_BUILD_STAMP): $(RUNTIME_BUILD_STAMP)
+$(PLAYGROUND_CMI_BUILD_STAMP): $(RUNTIME_BUILD_STAMP) $(BELT_BUILD_STAMP)
 	yarn workspace playground build
 
 playground-test: playground
diff --git a/analysis/src/semantic_tokens.ml b/analysis/src/semantic_tokens.ml
index 8a0bda9dc82..3e69d89a978 100644
--- a/analysis/src/semantic_tokens.ml
+++ b/analysis/src/semantic_tokens.ml
@@ -257,8 +257,9 @@ let command ~debug ~emitter ~source ~kind_file =
           (* Don't emit semantic tokens for identifiers not present in source code *)
           let should_emit =
             match lid with
-            (* Array spread (`...`) is converted to `Belt.Array.concatMany` with `@res.spread` decorator *)
-            | Ldot (Ldot (Lident "Belt", "Array"), "concatMany") ->
+            (* Collection spreads (`...`) are converted to primitive spread calls
+               with an `@res.spread` decorator. *)
+            | Ldot (Lident ("Primitive_array" | "Primitive_list"), "spread") ->
               let has_spread_attr =
                 e.pexp_attributes
                 |> List.exists (fun ({Location.txt}, _) -> txt = "res.spread")
diff --git a/biome.json b/biome.json
index 25d919de027..94358cad64f 100644
--- a/biome.json
+++ b/biome.json
@@ -55,6 +55,7 @@
       "!**/.yarn",
       "!**/tests/analysis_tests/**/src",
       "!**/tests/build_tests/**/src",
+      "!**/tests/belt_tests/**/src",
       "!**/tests/commonjs_tests/src",
       "!**/tests/dependencies/**/src",
       "!**/tests/docstring_tests",
diff --git a/compiler/core/outcome_printer_ns.ml b/compiler/core/outcome_printer_ns.ml
index 6163bf3433e..f9179e28d5a 100644
--- a/compiler/core/outcome_printer_ns.ml
+++ b/compiler/core/outcome_printer_ns.ml
@@ -26,38 +26,6 @@ let ps = Format.pp_print_string
 
 let out_ident ppf s =
   ps ppf
-    (match s with
-    (* Belt_libs  *)
-    | "Belt_Id" -> "Belt.Id"
-    | "Belt_Array" -> "Belt.Array"
-    | "Belt_SortArray" -> "Belt.SortArray"
-    | "Belt_SortArrayInt" -> "Belt.SortArray.Int"
-    | "Belt_SortArrayString" -> "Belt.SortArray.String"
-    | "Belt_MutableQueue" -> "Belt.MutableQueue"
-    | "Belt_MutableStack" -> "Belt.MutableStack"
-    | "Belt_List" -> "Belt.List"
-    | "Belt_Range" -> "Belt.Range"
-    | "Belt_Set" -> "Belt.Set"
-    | "Belt_SetInt" -> "Belt.Set.Int"
-    | "Belt_SetString" -> "Belt.Set.String"
-    | "Belt_Map" -> "Belt.Map"
-    | "Belt_MapInt" -> "Belt.Map.Int"
-    | "Belt_MapString" -> "Belt.Map.String"
-    | "Belt_Option" -> "Belt.Option"
-    | "Belt_MutableSet" -> "Belt.MutableSet"
-    | "Belt_MutableSetInt" -> "Belt.MutableSet.Int"
-    | "Belt_MutableSetString" -> "Belt.MutableSet.String"
-    | "Belt_MutableMap" -> "Belt.MutableMap"
-    | "Belt_MutableMapInt" -> "Belt.MutableMap.Int"
-    | "Belt_MutableMapString" -> "Belt.MutableMap.String"
-    | "Belt_HashSet" -> "Belt.HashSet"
-    | "Belt_HashSetInt" -> "Belt.HashSet.Int"
-    | "Belt_HashSetString" -> "Belt.HashSet.String"
-    | "Belt_HashMap" -> "Belt.HashMap"
-    | "Belt_HashMapString" -> "Belt.HashMap.String"
-    | "Belt_HashMapInt" -> "Belt.HashMap.Int"
-    | "Belt_Debug" -> "Belt.Debug"
-    | s -> (
-      match Ext_namespace.try_split_module_name s with
-      | None -> s
-      | Some (ns, m) -> ns ^ "." ^ m))
+    (match Ext_namespace.try_split_module_name s with
+    | None -> s
+    | Some (ns, m) -> ns ^ "." ^ m)
diff --git a/compiler/ext/primitive_modules.ml b/compiler/ext/primitive_modules.ml
index bff1d8b58a4..3a567de5242 100644
--- a/compiler/ext/primitive_modules.ml
+++ b/compiler/ext/primitive_modules.ml
@@ -34,6 +34,8 @@ let string = "Primitive_string"
 
 let array = "Primitive_array"
 
+let list = "Primitive_list"
+
 let dict = "Primitive_dict"
 
 let object_ = "Primitive_object"
diff --git a/compiler/frontend/bs_builtin_ppx.ml b/compiler/frontend/bs_builtin_ppx.ml
index 40e9ff79bfb..ae63e0d4b4a 100644
--- a/compiler/frontend/bs_builtin_ppx.ml
+++ b/compiler/frontend/bs_builtin_ppx.ml
@@ -73,7 +73,7 @@ let pat_mapper (self : mapper) (p : Parsetree.pattern) =
   | _ -> default_pat_mapper self p
 
 (* Unpack requires core_type package for type inference:
-   Generate a module type name eg. __Belt_List__*)
+   Generate a module type name eg. __List__*)
 let local_module_type_name txt =
   "_"
   ^ (Longident.flatten txt |> List.fold_left (fun ll l -> ll ^ "_" ^ l) "")
@@ -323,7 +323,7 @@ let expr_mapper ~async_context ~in_function_def (self : mapper)
      the attribute to the whole expression, in general, when shuffuling the ast
      it is very hard to place attributes correctly
   *)
-  (* module M = await Belt.List *)
+  (* module M = await List *)
   | Pexp_letmodule
       (lid, ({pmod_desc = Pmod_ident {txt}; pmod_attributes} as me), expr)
     when Res_parsetree_viewer.has_await_attribute pmod_attributes ->
@@ -339,7 +339,7 @@ let expr_mapper ~async_context ~in_function_def (self : mapper)
               ~module_type_lid:safe_module_type_lid me,
             self.expr self expr );
     }
-  (* module M = await (Belt.List: BeltList) *)
+  (* module M = await (List: ListType) *)
   | Pexp_letmodule
       ( lid,
         ({
@@ -661,7 +661,7 @@ let rec structure_mapper ~await_context (self : mapper) (stru : Ast_structure.t)
         | _ -> expand_reverse acc (structure_mapper ~await_context self rest)
       in
       aux [] stru
-    (* Dynamic import of module transformation: module M = @res.await Belt.List *)
+    (* Dynamic import of module transformation: module M = @res.await List *)
     | Pstr_module
         ({pmb_expr = {pmod_desc = Pmod_ident {txt; loc}; pmod_attributes} as me}
          as mb)
@@ -671,7 +671,7 @@ let rec structure_mapper ~await_context (self : mapper) (stru : Ast_structure.t)
       let has_local_module_name =
         Hashtbl.find_opt !await_context safe_module_type_name
       in
-      (* module __Belt_List__ = module type of Belt.List *)
+      (* module __List__ = module type of List *)
       let module_type_decl =
         match has_local_module_name with
         | Some _ -> []
@@ -690,7 +690,7 @@ let rec structure_mapper ~await_context (self : mapper) (stru : Ast_structure.t)
       in
       module_type_decl
       @
-      (* module M = @res.await Belt.List *)
+      (* module M = @res.await List *)
       {
         item with
         pstr_desc =
@@ -705,7 +705,7 @@ let rec structure_mapper ~await_context (self : mapper) (stru : Ast_structure.t)
       :: structure_mapper ~await_context self rest
     | Pstr_value (_, vbs) ->
       let item = self.structure_item self item in
-      (* [ module __Belt_List__ = module type of Belt.List ] *)
+      (* [ module __List__ = module type of List ] *)
       let rec spelunk_vbs acc vbs =
         match vbs with
         | [] -> acc
diff --git a/compiler/syntax/src/res_comments_table.ml b/compiler/syntax/src/res_comments_table.ml
index 1d0a470e52a..712aa2b87d1 100644
--- a/compiler/syntax/src/res_comments_table.ml
+++ b/compiler/syntax/src/res_comments_table.ml
@@ -1593,14 +1593,10 @@ and walk_expression expr t comments =
     when Res_parsetree_viewer.is_tuple_array key_values ->
     walk_list [Expression key_values] t comments
   | Pexp_apply {funct = call_expr; args = arguments} -> (
-    (* Special handling for Belt.Array.concatMany - treat like an array *)
+    (* Special handling for array spread - treat it like an array *)
     match call_expr.pexp_desc with
     | Pexp_ident
-        {
-          txt =
-            Longident.Ldot
-              (Longident.Ldot (Longident.Lident "Belt", "Array"), "concatMany");
-        }
+        {txt = Longident.Ldot (Longident.Lident "Primitive_array", "spread")}
       when List.length arguments = 1 -> (
       match arguments with
       | [(_, {pexp_desc = Pexp_array sub_arrays})] ->
diff --git a/compiler/syntax/src/res_core.ml b/compiler/syntax/src/res_core.ml
index 91b821a459d..cbdc8e319b4 100644
--- a/compiler/syntax/src/res_core.ml
+++ b/compiler/syntax/src/res_core.ml
@@ -4465,8 +4465,7 @@ and parse_list_expr ~start_pos p =
     Ast_helper.Exp.apply ~loc
       (Ast_helper.Exp.ident ~loc ~attrs:[spread_attr]
          (Location.mkloc
-            (Longident.Ldot
-               (Longident.Ldot (Longident.Lident "Belt", "List"), "concatMany"))
+            (Longident.Ldot (Longident.Lident Primitive_modules.list, "spread"))
             loc))
       [(Asttypes.Nolabel, Ast_helper.Exp.array ~loc list_exprs)]
 
@@ -4608,8 +4607,7 @@ and parse_array_exp p =
     Ast_helper.Exp.apply ~loc
       (Ast_helper.Exp.ident ~loc ~attrs:[spread_attr]
          (Location.mkloc
-            (Longident.Ldot
-               (Longident.Ldot (Longident.Lident "Belt", "Array"), "concatMany"))
+            (Longident.Ldot (Longident.Lident Primitive_modules.array, "spread"))
             loc))
       [(Nolabel, Ast_helper.Exp.array ~loc list_exprs)]
 
diff --git a/compiler/syntax/src/res_diagnostics.ml b/compiler/syntax/src/res_diagnostics.ml
index 76c39a39033..fc025169444 100644
--- a/compiler/syntax/src/res_diagnostics.ml
+++ b/compiler/syntax/src/res_diagnostics.ml
@@ -47,7 +47,7 @@ let explain t =
       let token = Token.to_string t in
       "`" ^ token ^ "` is a reserved keyword."
     | _ ->
-      "At this point, I'm looking for an uppercased name like `Belt` or `Array`"
+      "At this point, I'm looking for an uppercased name like `Array` or `Math`"
     )
   | Lident current_token -> (
     match current_token with
diff --git a/compiler/syntax/src/res_grammar.ml b/compiler/syntax/src/res_grammar.ml
index de4a9578064..1d21062fcfd 100644
--- a/compiler/syntax/src/res_grammar.ml
+++ b/compiler/syntax/src/res_grammar.ml
@@ -1,7 +1,7 @@
 module Token = Res_token
 
 type t =
-  | OpenDescription (* open Belt *)
+  | OpenDescription (* open Array *)
   | ModuleLongIdent (* Foo or Foo.Bar *) [@live]
   | Ternary (* condExpr ? trueExpr : falseExpr *)
   | Es6ArrowExpr
diff --git a/compiler/syntax/src/res_parsetree_viewer.ml b/compiler/syntax/src/res_parsetree_viewer.ml
index 5a0301dbc7a..508acba1e3f 100644
--- a/compiler/syntax/src/res_parsetree_viewer.ml
+++ b/compiler/syntax/src/res_parsetree_viewer.ml
@@ -726,25 +726,17 @@ let has_spread_attr attrs =
       | _ -> false)
     attrs
 
-let is_spread_belt_list_concat expr =
+let is_spread_list expr =
   match expr.pexp_desc with
   | Pexp_ident
-      {
-        txt =
-          Longident.Ldot
-            (Longident.Ldot (Longident.Lident "Belt", "List"), "concatMany");
-      } ->
+      {txt = Longident.Ldot (Longident.Lident "Primitive_list", "spread")} ->
     has_spread_attr expr.pexp_attributes
   | _ -> false
 
-let is_spread_belt_array_concat expr =
+let is_spread_array expr =
   match expr.pexp_desc with
   | Pexp_ident
-      {
-        txt =
-          Longident.Ldot
-            (Longident.Ldot (Longident.Lident "Belt", "Array"), "concatMany");
-      } ->
+      {txt = Longident.Ldot (Longident.Lident "Primitive_array", "spread")} ->
     has_spread_attr expr.pexp_attributes
   | _ -> false
 
diff --git a/compiler/syntax/src/res_parsetree_viewer.mli b/compiler/syntax/src/res_parsetree_viewer.mli
index 8d4536717fe..5fc8c74e877 100644
--- a/compiler/syntax/src/res_parsetree_viewer.mli
+++ b/compiler/syntax/src/res_parsetree_viewer.mli
@@ -133,9 +133,9 @@ val is_template_literal : Parsetree.expression -> bool
 val is_tagged_template_literal : Parsetree.expression -> bool
 val has_template_literal_attr : Parsetree.attributes -> bool
 
-val is_spread_belt_list_concat : Parsetree.expression -> bool
+val is_spread_list : Parsetree.expression -> bool
 
-val is_spread_belt_array_concat : Parsetree.expression -> bool
+val is_spread_array : Parsetree.expression -> bool
 
 val collect_spread_dict_expr_parts :
   Parsetree.expression -> dict_expr_part list option
diff --git a/compiler/syntax/src/res_printer.ml b/compiler/syntax/src/res_printer.ml
index da48b02561e..820e5461244 100644
--- a/compiler/syntax/src/res_printer.ml
+++ b/compiler/syntax/src/res_printer.ml
@@ -2453,7 +2453,7 @@ and print_value_binding ~state ~rec_flag (vb : Parsetree.value_binding) cmt_tbl
      *   let decoratorTags =
      *     items
      *     ->Array.filter(items => {items.category === Decorators})
-     *     ->Belt.Array.map(...)
+     *     ->Array.map(...)
      * Multiple pipes chained together lend themselves more towards the last layout.
      *)
     if Parsetree_viewer.is_single_pipe_expr vb.pvb_expr then
@@ -3583,12 +3583,12 @@ and print_expression ~state (e : Parsetree.expression) cmt_tbl =
         print_extension ~state ~at_module_lvl:false extension cmt_tbl)
     | Pexp_apply
         {funct = e; args = [(Nolabel, {pexp_desc = Pexp_array sub_lists})]}
-      when Parsetree_viewer.is_spread_belt_array_concat e ->
-      print_belt_array_concat_apply ~state sub_lists cmt_tbl
+      when Parsetree_viewer.is_spread_array e ->
+      print_array_spread_apply ~state sub_lists cmt_tbl
     | Pexp_apply
         {funct = e; args = [(Nolabel, {pexp_desc = Pexp_array sub_lists})]}
-      when Parsetree_viewer.is_spread_belt_list_concat e ->
-      print_belt_list_concat_apply ~state sub_lists cmt_tbl
+      when Parsetree_viewer.is_spread_list e ->
+      print_list_spread_apply ~state sub_lists cmt_tbl
     | Pexp_apply {funct = call_expr; args} ->
       if Parsetree_viewer.is_unary_expression e then
         print_unary_expression ~state e cmt_tbl
@@ -4381,7 +4381,7 @@ and print_binary_expression ~state (expr : Parsetree.expression) cmt_tbl =
          ])
   | _ -> Doc.nil
 
-and print_belt_array_concat_apply ~state sub_lists cmt_tbl =
+and print_array_spread_apply ~state sub_lists cmt_tbl =
   let make_spread_doc comma_before_spread = function
     | Some expr ->
       (* Extract leading comments before dotdotdot *)
@@ -4451,7 +4451,7 @@ and print_belt_array_concat_apply ~state sub_lists cmt_tbl =
          Doc.rbracket;
        ])
 
-and print_belt_list_concat_apply ~state sub_lists cmt_tbl =
+and print_list_spread_apply ~state sub_lists cmt_tbl =
   let make_spread_doc comma_before_spread = function
     | Some expr ->
       Doc.concat
diff --git a/docs/JSXV4.md b/docs/JSXV4.md
index 927de6b0a63..d7657e2c88b 100644
--- a/docs/JSXV4.md
+++ b/docs/JSXV4.md
@@ -165,7 +165,7 @@ module FancyInput = {
       <input
         type_="text"
         ?className
-        ref=?{ref_->Nullable.toOption->Belt.Option.map(ReactDOM.Ref.domRef)}
+        ref=?{ref_->Nullable.toOption->Option.map(ReactDOM.Ref.domRef)}
       />
       children
     </div>
@@ -198,7 +198,7 @@ module FancyInput = {
       <input
         type_="text"
         ?className
-        ref=?{ref->Nullable.toOption->Belt.Option.map(ReactDOM.Ref.domRef)}
+        ref=?{ref->Nullable.toOption->Option.map(ReactDOM.Ref.domRef)}
       />
       children
     </div>
diff --git a/package.json b/package.json
index c0a45689a10..50c42cffed2 100644
--- a/package.json
+++ b/package.json
@@ -103,6 +103,7 @@
     "tests/dependencies/**",
     "tests/analysis_tests/**",
     "tests/docstring_tests",
+    "tests/belt_tests",
     "tests/gentype_tests/**",
     "tests/tests",
     "tests/tools_tests",
diff --git a/packages/@rescript/belt/.gitignore b/packages/@rescript/belt/.gitignore
new file mode 100644
index 00000000000..4673ed827b1
--- /dev/null
+++ b/packages/@rescript/belt/.gitignore
@@ -0,0 +1,13 @@
+lib/bs
+lib/ocaml
+*.lock
+.buildstamp
+bs/
+*.ast
+*.iast
+rescript.lock
+.compiler.log
+src/*.js
+src/*.mjs
+src/*.cjs
+lib/**/*.res.js
diff --git a/packages/@rescript/belt/README.md b/packages/@rescript/belt/README.md
new file mode 100644
index 00000000000..8d76ace8ad3
--- /dev/null
+++ b/packages/@rescript/belt/README.md
@@ -0,0 +1,24 @@
+# @rescript/belt
+
+Belt is an extended utility and collection library for ReScript. It provides performance-oriented
+collection types, with a particular emphasis on immutable collections, alongside utility modules
+for common data types and operations. Belt is distributed separately from the compiler and standard
+library.
+
+## Installation
+
+Install the package with your package manager:
+
+```sh
+npm install @rescript/belt
+```
+
+Then add it to your `rescript.json` dependencies:
+
+```json
+{
+  "dependencies": ["@rescript/belt"]
+}
+```
+
+Belt is not opened automatically. Use modules through names such as `Belt.Array` and `Belt.Map`, or explicitly `open Belt` in source files that should use the shorter module names.
diff --git a/packages/@rescript/runtime/lib/es6/Belt.mjs b/packages/@rescript/belt/lib/es6/src/Belt.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Array.mjs b/packages/@rescript/belt/lib/es6/src/Belt_Array.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_Array.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_Array.mjs
index f693ae6d07b..bfc5abcc70d 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_Array.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_Array.mjs
@@ -1,7 +1,7 @@
 
 
-import * as Primitive_int from "./Primitive_int.mjs";
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function get(arr, i) {
   if (i >= 0 && i < arr.length) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Float.mjs b/packages/@rescript/belt/lib/es6/src/Belt_Float.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_Float.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_Float.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_HashMap.mjs b/packages/@rescript/belt/lib/es6/src/Belt_HashMap.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_HashMap.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_HashMap.mjs
index 52ed52a0c4c..c45922bb7a7 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_HashMap.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_HashMap.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalBuckets from "./Belt_internalBuckets.mjs";
 import * as Belt_internalBucketsType from "./Belt_internalBucketsType.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_HashMapInt.mjs b/packages/@rescript/belt/lib/es6/src/Belt_HashMapInt.mjs
similarity index 97%
rename from packages/@rescript/runtime/lib/es6/Belt_HashMapInt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_HashMapInt.mjs
index 9373d41805e..28fd20910a6 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_HashMapInt.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_HashMapInt.mjs
@@ -1,7 +1,7 @@
 
 
-import * as Primitive_hash from "./Primitive_hash.mjs";
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_hash from "@rescript/runtime/lib/es6/Primitive_hash.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalBuckets from "./Belt_internalBuckets.mjs";
 import * as Belt_internalBucketsType from "./Belt_internalBucketsType.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_HashMapString.mjs b/packages/@rescript/belt/lib/es6/src/Belt_HashMapString.mjs
similarity index 97%
rename from packages/@rescript/runtime/lib/es6/Belt_HashMapString.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_HashMapString.mjs
index 18a340640e8..19a9d71371f 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_HashMapString.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_HashMapString.mjs
@@ -1,7 +1,7 @@
 
 
-import * as Primitive_hash from "./Primitive_hash.mjs";
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_hash from "@rescript/runtime/lib/es6/Primitive_hash.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalBuckets from "./Belt_internalBuckets.mjs";
 import * as Belt_internalBucketsType from "./Belt_internalBucketsType.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_HashSet.mjs b/packages/@rescript/belt/lib/es6/src/Belt_HashSet.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_HashSet.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_HashSet.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_HashSetInt.mjs b/packages/@rescript/belt/lib/es6/src/Belt_HashSetInt.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_HashSetInt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_HashSetInt.mjs
index aecdec398d6..79494aff019 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_HashSetInt.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_HashSetInt.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_hash from "./Primitive_hash.mjs";
+import * as Primitive_hash from "@rescript/runtime/lib/es6/Primitive_hash.mjs";
 import * as Belt_internalSetBuckets from "./Belt_internalSetBuckets.mjs";
 import * as Belt_internalBucketsType from "./Belt_internalBucketsType.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_HashSetString.mjs b/packages/@rescript/belt/lib/es6/src/Belt_HashSetString.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_HashSetString.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_HashSetString.mjs
index 7c1b6b2a439..d06ccf8445e 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_HashSetString.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_HashSetString.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_hash from "./Primitive_hash.mjs";
+import * as Primitive_hash from "@rescript/runtime/lib/es6/Primitive_hash.mjs";
 import * as Belt_internalSetBuckets from "./Belt_internalSetBuckets.mjs";
 import * as Belt_internalBucketsType from "./Belt_internalBucketsType.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Id.mjs b/packages/@rescript/belt/lib/es6/src/Belt_Id.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_Id.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_Id.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Int.mjs b/packages/@rescript/belt/lib/es6/src/Belt_Int.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_Int.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_Int.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_List.mjs b/packages/@rescript/belt/lib/es6/src/Belt_List.mjs
similarity index 99%
rename from packages/@rescript/runtime/lib/es6/Belt_List.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_List.mjs
index f1942b4b659..80cd51490a8 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_List.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_List.mjs
@@ -2,7 +2,7 @@
 
 import * as Belt_Array from "./Belt_Array.mjs";
 import * as Belt_SortArray from "./Belt_SortArray.mjs";
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function head(x) {
   if (x !== 0) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Map.mjs b/packages/@rescript/belt/lib/es6/src/Belt_Map.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_Map.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_Map.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MapDict.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MapDict.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_MapDict.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MapDict.mjs
index cd6869b361e..5a226ffb174 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MapDict.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MapDict.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalAVLtree from "./Belt_internalAVLtree.mjs";
 
 function set(t, newK, newD, cmp) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MapInt.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MapInt.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_MapInt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MapInt.mjs
index 15535ae39c4..d0e96b75908 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MapInt.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MapInt.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalMapInt from "./Belt_internalMapInt.mjs";
 import * as Belt_internalAVLtree from "./Belt_internalAVLtree.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MapString.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MapString.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_MapString.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MapString.mjs
index 4eccd3c5a21..a80f7eb6efa 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MapString.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MapString.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalAVLtree from "./Belt_internalAVLtree.mjs";
 import * as Belt_internalMapString from "./Belt_internalMapString.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableMap.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MutableMap.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_MutableMap.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MutableMap.mjs
index 6904df72a89..1946813b92c 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableMap.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MutableMap.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalAVLtree from "./Belt_internalAVLtree.mjs";
 
 function removeMutateAux(nt, x, cmp) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableMapInt.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MutableMapInt.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_MutableMapInt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MutableMapInt.mjs
index c7a5111a0f8..a45deb1acc0 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableMapInt.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MutableMapInt.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalMapInt from "./Belt_internalMapInt.mjs";
 import * as Belt_internalAVLtree from "./Belt_internalAVLtree.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableMapString.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MutableMapString.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_MutableMapString.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MutableMapString.mjs
index 12c23b010ba..7e4683ebadf 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableMapString.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MutableMapString.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalAVLtree from "./Belt_internalAVLtree.mjs";
 import * as Belt_internalMapString from "./Belt_internalMapString.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableQueue.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MutableQueue.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_MutableQueue.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MutableQueue.mjs
index 2640eed1e5c..d31e683f522 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableQueue.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MutableQueue.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function make() {
   return {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableSet.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MutableSet.mjs
similarity index 99%
rename from packages/@rescript/runtime/lib/es6/Belt_MutableSet.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MutableSet.mjs
index 0f52938a482..157629c2fa0 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableSet.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MutableSet.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_int from "./Primitive_int.mjs";
+import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Belt_SortArray from "./Belt_SortArray.mjs";
 import * as Belt_internalAVLset from "./Belt_internalAVLset.mjs";
 
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableSetInt.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MutableSetInt.mjs
similarity index 99%
rename from packages/@rescript/runtime/lib/es6/Belt_MutableSetInt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MutableSetInt.mjs
index 659782e9189..569e1aa5f09 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableSetInt.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MutableSetInt.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_int from "./Primitive_int.mjs";
+import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Belt_SortArrayInt from "./Belt_SortArrayInt.mjs";
 import * as Belt_internalAVLset from "./Belt_internalAVLset.mjs";
 import * as Belt_internalSetInt from "./Belt_internalSetInt.mjs";
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableSetString.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MutableSetString.mjs
similarity index 99%
rename from packages/@rescript/runtime/lib/es6/Belt_MutableSetString.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MutableSetString.mjs
index f63cac40468..202698b5850 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableSetString.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MutableSetString.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_int from "./Primitive_int.mjs";
+import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Belt_internalAVLset from "./Belt_internalAVLset.mjs";
 import * as Belt_SortArrayString from "./Belt_SortArrayString.mjs";
 import * as Belt_internalSetString from "./Belt_internalSetString.mjs";
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableStack.mjs b/packages/@rescript/belt/lib/es6/src/Belt_MutableStack.mjs
similarity index 95%
rename from packages/@rescript/runtime/lib/es6/Belt_MutableStack.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_MutableStack.mjs
index 25797286152..44aa615c1b0 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableStack.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_MutableStack.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function make() {
   return {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Option.mjs b/packages/@rescript/belt/lib/es6/src/Belt_Option.mjs
similarity index 96%
rename from packages/@rescript/runtime/lib/es6/Belt_Option.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_Option.mjs
index 313c0d158ec..7b28bdb38a1 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_Option.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_Option.mjs
@@ -1,6 +1,6 @@
 
 
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function keep(opt, p) {
   if (opt !== undefined && p(Primitive_option.valFromOption(opt))) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Range.mjs b/packages/@rescript/belt/lib/es6/src/Belt_Range.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_Range.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_Range.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Result.mjs b/packages/@rescript/belt/lib/es6/src/Belt_Result.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_Result.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_Result.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Set.mjs b/packages/@rescript/belt/lib/es6/src/Belt_Set.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_Set.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_Set.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_SetDict.mjs b/packages/@rescript/belt/lib/es6/src/Belt_SetDict.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_SetDict.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_SetDict.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_SetInt.mjs b/packages/@rescript/belt/lib/es6/src/Belt_SetInt.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_SetInt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_SetInt.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_SetString.mjs b/packages/@rescript/belt/lib/es6/src/Belt_SetString.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_SetString.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_SetString.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_SortArray.mjs b/packages/@rescript/belt/lib/es6/src/Belt_SortArray.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_SortArray.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_SortArray.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_SortArrayInt.mjs b/packages/@rescript/belt/lib/es6/src/Belt_SortArrayInt.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_SortArrayInt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_SortArrayInt.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_SortArrayString.mjs b/packages/@rescript/belt/lib/es6/src/Belt_SortArrayString.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_SortArrayString.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_SortArrayString.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalAVLset.mjs b/packages/@rescript/belt/lib/es6/src/Belt_internalAVLset.mjs
similarity index 98%
rename from packages/@rescript/runtime/lib/es6/Belt_internalAVLset.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_internalAVLset.mjs
index f679e28aaf3..835d8e243c7 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalAVLset.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_internalAVLset.mjs
@@ -1,8 +1,8 @@
 
 
-import * as Primitive_int from "./Primitive_int.mjs";
+import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Belt_SortArray from "./Belt_SortArray.mjs";
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function copy(n) {
   if (n !== undefined) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalAVLtree.mjs b/packages/@rescript/belt/lib/es6/src/Belt_internalAVLtree.mjs
similarity index 99%
rename from packages/@rescript/runtime/lib/es6/Belt_internalAVLtree.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_internalAVLtree.mjs
index 6f5f86f0aee..b362de4ec2a 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalAVLtree.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_internalAVLtree.mjs
@@ -1,8 +1,8 @@
 
 
-import * as Primitive_int from "./Primitive_int.mjs";
+import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Belt_SortArray from "./Belt_SortArray.mjs";
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function treeHeight(n) {
   if (n !== undefined) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalBuckets.mjs b/packages/@rescript/belt/lib/es6/src/Belt_internalBuckets.mjs
similarity index 96%
rename from packages/@rescript/runtime/lib/es6/Belt_internalBuckets.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_internalBuckets.mjs
index 0ccc15c2f18..b050532526d 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalBuckets.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_internalBuckets.mjs
@@ -1,8 +1,8 @@
 
 
 import * as Belt_Array from "./Belt_Array.mjs";
-import * as Primitive_int from "./Primitive_int.mjs";
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function copyBucket(c) {
   if (c === undefined) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalBucketsType.mjs b/packages/@rescript/belt/lib/es6/src/Belt_internalBucketsType.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_internalBucketsType.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_internalBucketsType.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalMapInt.mjs b/packages/@rescript/belt/lib/es6/src/Belt_internalMapInt.mjs
similarity index 97%
rename from packages/@rescript/runtime/lib/es6/Belt_internalMapInt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_internalMapInt.mjs
index 687fca236e3..d1902be3004 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalMapInt.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_internalMapInt.mjs
@@ -1,8 +1,8 @@
 
 
-import * as Primitive_int from "./Primitive_int.mjs";
+import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Belt_SortArray from "./Belt_SortArray.mjs";
-import * as Primitive_option from "./Primitive_option.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Belt_internalAVLtree from "./Belt_internalAVLtree.mjs";
 
 function add(t, x, data) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalMapString.mjs b/packages/@rescript/belt/lib/es6/src/Belt_internalMapString.mjs
similarity index 97%
rename from packages/@rescript/runtime/lib/es6/Belt_internalMapString.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_internalMapString.mjs
index 8db48ead6a5..45a0f989301 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalMapString.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_internalMapString.mjs
@@ -1,8 +1,8 @@
 
 
 import * as Belt_SortArray from "./Belt_SortArray.mjs";
-import * as Primitive_option from "./Primitive_option.mjs";
-import * as Primitive_string from "./Primitive_string.mjs";
+import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
+import * as Primitive_string from "@rescript/runtime/lib/es6/Primitive_string.mjs";
 import * as Belt_internalAVLtree from "./Belt_internalAVLtree.mjs";
 
 function add(t, x, data) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalSetBuckets.mjs b/packages/@rescript/belt/lib/es6/src/Belt_internalSetBuckets.mjs
similarity index 97%
rename from packages/@rescript/runtime/lib/es6/Belt_internalSetBuckets.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_internalSetBuckets.mjs
index d7a0b685873..9d060ba5e26 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalSetBuckets.mjs
+++ b/packages/@rescript/belt/lib/es6/src/Belt_internalSetBuckets.mjs
@@ -1,7 +1,7 @@
 
 
 import * as Belt_Array from "./Belt_Array.mjs";
-import * as Primitive_int from "./Primitive_int.mjs";
+import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 
 function copyAuxCont(_c, _prec) {
   while (true) {
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalSetInt.mjs b/packages/@rescript/belt/lib/es6/src/Belt_internalSetInt.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_internalSetInt.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_internalSetInt.mjs
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalSetString.mjs b/packages/@rescript/belt/lib/es6/src/Belt_internalSetString.mjs
similarity index 100%
rename from packages/@rescript/runtime/lib/es6/Belt_internalSetString.mjs
rename to packages/@rescript/belt/lib/es6/src/Belt_internalSetString.mjs
diff --git a/packages/@rescript/runtime/lib/js/Belt.cjs b/packages/@rescript/belt/lib/js/src/Belt.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_Array.cjs b/packages/@rescript/belt/lib/js/src/Belt_Array.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_Array.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_Array.cjs
index cbc613a08fc..e922e627206 100644
--- a/packages/@rescript/runtime/lib/js/Belt_Array.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_Array.cjs
@@ -1,7 +1,7 @@
 'use strict';
 
-let Primitive_int = require("./Primitive_int.cjs");
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_int = require("@rescript/runtime/lib/js/Primitive_int.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 
 function get(arr, i) {
   if (i >= 0 && i < arr.length) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_Float.cjs b/packages/@rescript/belt/lib/js/src/Belt_Float.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_Float.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_Float.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_HashMap.cjs b/packages/@rescript/belt/lib/js/src/Belt_HashMap.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_HashMap.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_HashMap.cjs
index 6d25fbdcaac..15e97e99393 100644
--- a/packages/@rescript/runtime/lib/js/Belt_HashMap.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_HashMap.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalBuckets = require("./Belt_internalBuckets.cjs");
 let Belt_internalBucketsType = require("./Belt_internalBucketsType.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_HashMapInt.cjs b/packages/@rescript/belt/lib/js/src/Belt_HashMapInt.cjs
similarity index 97%
rename from packages/@rescript/runtime/lib/js/Belt_HashMapInt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_HashMapInt.cjs
index c713033b200..8bea56463a1 100644
--- a/packages/@rescript/runtime/lib/js/Belt_HashMapInt.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_HashMapInt.cjs
@@ -1,7 +1,7 @@
 'use strict';
 
-let Primitive_hash = require("./Primitive_hash.cjs");
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_hash = require("@rescript/runtime/lib/js/Primitive_hash.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalBuckets = require("./Belt_internalBuckets.cjs");
 let Belt_internalBucketsType = require("./Belt_internalBucketsType.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_HashMapString.cjs b/packages/@rescript/belt/lib/js/src/Belt_HashMapString.cjs
similarity index 97%
rename from packages/@rescript/runtime/lib/js/Belt_HashMapString.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_HashMapString.cjs
index 920ca94866b..89e80544db3 100644
--- a/packages/@rescript/runtime/lib/js/Belt_HashMapString.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_HashMapString.cjs
@@ -1,7 +1,7 @@
 'use strict';
 
-let Primitive_hash = require("./Primitive_hash.cjs");
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_hash = require("@rescript/runtime/lib/js/Primitive_hash.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalBuckets = require("./Belt_internalBuckets.cjs");
 let Belt_internalBucketsType = require("./Belt_internalBucketsType.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_HashSet.cjs b/packages/@rescript/belt/lib/js/src/Belt_HashSet.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_HashSet.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_HashSet.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_HashSetInt.cjs b/packages/@rescript/belt/lib/js/src/Belt_HashSetInt.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_HashSetInt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_HashSetInt.cjs
index 564029100ae..01dd05804a4 100644
--- a/packages/@rescript/runtime/lib/js/Belt_HashSetInt.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_HashSetInt.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_hash = require("./Primitive_hash.cjs");
+let Primitive_hash = require("@rescript/runtime/lib/js/Primitive_hash.cjs");
 let Belt_internalSetBuckets = require("./Belt_internalSetBuckets.cjs");
 let Belt_internalBucketsType = require("./Belt_internalBucketsType.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_HashSetString.cjs b/packages/@rescript/belt/lib/js/src/Belt_HashSetString.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_HashSetString.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_HashSetString.cjs
index 9c1c0df6948..9299a94e43c 100644
--- a/packages/@rescript/runtime/lib/js/Belt_HashSetString.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_HashSetString.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_hash = require("./Primitive_hash.cjs");
+let Primitive_hash = require("@rescript/runtime/lib/js/Primitive_hash.cjs");
 let Belt_internalSetBuckets = require("./Belt_internalSetBuckets.cjs");
 let Belt_internalBucketsType = require("./Belt_internalBucketsType.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_Id.cjs b/packages/@rescript/belt/lib/js/src/Belt_Id.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_Id.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_Id.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_Int.cjs b/packages/@rescript/belt/lib/js/src/Belt_Int.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_Int.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_Int.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_List.cjs b/packages/@rescript/belt/lib/js/src/Belt_List.cjs
similarity index 99%
rename from packages/@rescript/runtime/lib/js/Belt_List.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_List.cjs
index 1806112a8b4..79a68924b86 100644
--- a/packages/@rescript/runtime/lib/js/Belt_List.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_List.cjs
@@ -2,7 +2,7 @@
 
 let Belt_Array = require("./Belt_Array.cjs");
 let Belt_SortArray = require("./Belt_SortArray.cjs");
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 
 function head(x) {
   if (x !== 0) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_Map.cjs b/packages/@rescript/belt/lib/js/src/Belt_Map.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_Map.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_Map.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_MapDict.cjs b/packages/@rescript/belt/lib/js/src/Belt_MapDict.cjs
similarity index 99%
rename from packages/@rescript/runtime/lib/js/Belt_MapDict.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MapDict.cjs
index 2da494c41ec..ef04c8d6662 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MapDict.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MapDict.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalAVLtree = require("./Belt_internalAVLtree.cjs");
 
 function set(t, newK, newD, cmp) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_MapInt.cjs b/packages/@rescript/belt/lib/js/src/Belt_MapInt.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_MapInt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MapInt.cjs
index 468f503562c..efcbb75ea35 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MapInt.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MapInt.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalMapInt = require("./Belt_internalMapInt.cjs");
 let Belt_internalAVLtree = require("./Belt_internalAVLtree.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_MapString.cjs b/packages/@rescript/belt/lib/js/src/Belt_MapString.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_MapString.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MapString.cjs
index e68674e64e4..efd44ddfaf5 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MapString.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MapString.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalAVLtree = require("./Belt_internalAVLtree.cjs");
 let Belt_internalMapString = require("./Belt_internalMapString.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableMap.cjs b/packages/@rescript/belt/lib/js/src/Belt_MutableMap.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_MutableMap.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MutableMap.cjs
index e1c5bd40e81..ea90a5cf8d7 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableMap.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MutableMap.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalAVLtree = require("./Belt_internalAVLtree.cjs");
 
 function removeMutateAux(nt, x, cmp) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableMapInt.cjs b/packages/@rescript/belt/lib/js/src/Belt_MutableMapInt.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_MutableMapInt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MutableMapInt.cjs
index bb296711ee2..2198e278b30 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableMapInt.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MutableMapInt.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalMapInt = require("./Belt_internalMapInt.cjs");
 let Belt_internalAVLtree = require("./Belt_internalAVLtree.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableMapString.cjs b/packages/@rescript/belt/lib/js/src/Belt_MutableMapString.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_MutableMapString.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MutableMapString.cjs
index 27dabb44a7b..5cf59381770 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableMapString.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MutableMapString.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalAVLtree = require("./Belt_internalAVLtree.cjs");
 let Belt_internalMapString = require("./Belt_internalMapString.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableQueue.cjs b/packages/@rescript/belt/lib/js/src/Belt_MutableQueue.cjs
similarity index 98%
rename from packages/@rescript/runtime/lib/js/Belt_MutableQueue.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MutableQueue.cjs
index 6fd919d3f1b..95842f5c257 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableQueue.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MutableQueue.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 
 function make() {
   return {
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableSet.cjs b/packages/@rescript/belt/lib/js/src/Belt_MutableSet.cjs
similarity index 99%
rename from packages/@rescript/runtime/lib/js/Belt_MutableSet.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MutableSet.cjs
index 2d44004d261..9227552a6c1 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableSet.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MutableSet.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_int = require("./Primitive_int.cjs");
+let Primitive_int = require("@rescript/runtime/lib/js/Primitive_int.cjs");
 let Belt_SortArray = require("./Belt_SortArray.cjs");
 let Belt_internalAVLset = require("./Belt_internalAVLset.cjs");
 
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableSetInt.cjs b/packages/@rescript/belt/lib/js/src/Belt_MutableSetInt.cjs
similarity index 99%
rename from packages/@rescript/runtime/lib/js/Belt_MutableSetInt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MutableSetInt.cjs
index ef9d822b31e..93e86c0b314 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableSetInt.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MutableSetInt.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_int = require("./Primitive_int.cjs");
+let Primitive_int = require("@rescript/runtime/lib/js/Primitive_int.cjs");
 let Belt_SortArrayInt = require("./Belt_SortArrayInt.cjs");
 let Belt_internalAVLset = require("./Belt_internalAVLset.cjs");
 let Belt_internalSetInt = require("./Belt_internalSetInt.cjs");
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableSetString.cjs b/packages/@rescript/belt/lib/js/src/Belt_MutableSetString.cjs
similarity index 99%
rename from packages/@rescript/runtime/lib/js/Belt_MutableSetString.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MutableSetString.cjs
index b1abaccad1a..e2ca6a3320b 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableSetString.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MutableSetString.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_int = require("./Primitive_int.cjs");
+let Primitive_int = require("@rescript/runtime/lib/js/Primitive_int.cjs");
 let Belt_internalAVLset = require("./Belt_internalAVLset.cjs");
 let Belt_SortArrayString = require("./Belt_SortArrayString.cjs");
 let Belt_internalSetString = require("./Belt_internalSetString.cjs");
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableStack.cjs b/packages/@rescript/belt/lib/js/src/Belt_MutableStack.cjs
similarity index 95%
rename from packages/@rescript/runtime/lib/js/Belt_MutableStack.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_MutableStack.cjs
index d5899040684..79a188cf18f 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableStack.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_MutableStack.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 
 function make() {
   return {
diff --git a/packages/@rescript/runtime/lib/js/Belt_Option.cjs b/packages/@rescript/belt/lib/js/src/Belt_Option.cjs
similarity index 96%
rename from packages/@rescript/runtime/lib/js/Belt_Option.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_Option.cjs
index 0e272459701..7ba158656cd 100644
--- a/packages/@rescript/runtime/lib/js/Belt_Option.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_Option.cjs
@@ -1,6 +1,6 @@
 'use strict';
 
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 
 function keep(opt, p) {
   if (opt !== undefined && p(Primitive_option.valFromOption(opt))) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_Range.cjs b/packages/@rescript/belt/lib/js/src/Belt_Range.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_Range.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_Range.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_Result.cjs b/packages/@rescript/belt/lib/js/src/Belt_Result.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_Result.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_Result.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_Set.cjs b/packages/@rescript/belt/lib/js/src/Belt_Set.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_Set.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_Set.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_SetDict.cjs b/packages/@rescript/belt/lib/js/src/Belt_SetDict.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_SetDict.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_SetDict.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_SetInt.cjs b/packages/@rescript/belt/lib/js/src/Belt_SetInt.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_SetInt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_SetInt.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_SetString.cjs b/packages/@rescript/belt/lib/js/src/Belt_SetString.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_SetString.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_SetString.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_SortArray.cjs b/packages/@rescript/belt/lib/js/src/Belt_SortArray.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_SortArray.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_SortArray.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_SortArrayInt.cjs b/packages/@rescript/belt/lib/js/src/Belt_SortArrayInt.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_SortArrayInt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_SortArrayInt.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_SortArrayString.cjs b/packages/@rescript/belt/lib/js/src/Belt_SortArrayString.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_SortArrayString.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_SortArrayString.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalAVLset.cjs b/packages/@rescript/belt/lib/js/src/Belt_internalAVLset.cjs
similarity index 99%
rename from packages/@rescript/runtime/lib/js/Belt_internalAVLset.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_internalAVLset.cjs
index 50626ea185f..9be6177fa23 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalAVLset.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_internalAVLset.cjs
@@ -1,8 +1,8 @@
 'use strict';
 
-let Primitive_int = require("./Primitive_int.cjs");
+let Primitive_int = require("@rescript/runtime/lib/js/Primitive_int.cjs");
 let Belt_SortArray = require("./Belt_SortArray.cjs");
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 
 function copy(n) {
   if (n !== undefined) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalAVLtree.cjs b/packages/@rescript/belt/lib/js/src/Belt_internalAVLtree.cjs
similarity index 99%
rename from packages/@rescript/runtime/lib/js/Belt_internalAVLtree.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_internalAVLtree.cjs
index 1192eb13d88..f3901301301 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalAVLtree.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_internalAVLtree.cjs
@@ -1,8 +1,8 @@
 'use strict';
 
-let Primitive_int = require("./Primitive_int.cjs");
+let Primitive_int = require("@rescript/runtime/lib/js/Primitive_int.cjs");
 let Belt_SortArray = require("./Belt_SortArray.cjs");
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 
 function treeHeight(n) {
   if (n !== undefined) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalBuckets.cjs b/packages/@rescript/belt/lib/js/src/Belt_internalBuckets.cjs
similarity index 96%
rename from packages/@rescript/runtime/lib/js/Belt_internalBuckets.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_internalBuckets.cjs
index d257c24e91d..8f08e017521 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalBuckets.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_internalBuckets.cjs
@@ -1,8 +1,8 @@
 'use strict';
 
 let Belt_Array = require("./Belt_Array.cjs");
-let Primitive_int = require("./Primitive_int.cjs");
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_int = require("@rescript/runtime/lib/js/Primitive_int.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 
 function copyBucket(c) {
   if (c === undefined) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalBucketsType.cjs b/packages/@rescript/belt/lib/js/src/Belt_internalBucketsType.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_internalBucketsType.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_internalBucketsType.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalMapInt.cjs b/packages/@rescript/belt/lib/js/src/Belt_internalMapInt.cjs
similarity index 97%
rename from packages/@rescript/runtime/lib/js/Belt_internalMapInt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_internalMapInt.cjs
index 1c09a9c4e1b..44909443228 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalMapInt.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_internalMapInt.cjs
@@ -1,8 +1,8 @@
 'use strict';
 
-let Primitive_int = require("./Primitive_int.cjs");
+let Primitive_int = require("@rescript/runtime/lib/js/Primitive_int.cjs");
 let Belt_SortArray = require("./Belt_SortArray.cjs");
-let Primitive_option = require("./Primitive_option.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
 let Belt_internalAVLtree = require("./Belt_internalAVLtree.cjs");
 
 function add(t, x, data) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalMapString.cjs b/packages/@rescript/belt/lib/js/src/Belt_internalMapString.cjs
similarity index 97%
rename from packages/@rescript/runtime/lib/js/Belt_internalMapString.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_internalMapString.cjs
index 1ff5fa3cb08..0f3018d955e 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalMapString.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_internalMapString.cjs
@@ -1,8 +1,8 @@
 'use strict';
 
 let Belt_SortArray = require("./Belt_SortArray.cjs");
-let Primitive_option = require("./Primitive_option.cjs");
-let Primitive_string = require("./Primitive_string.cjs");
+let Primitive_option = require("@rescript/runtime/lib/js/Primitive_option.cjs");
+let Primitive_string = require("@rescript/runtime/lib/js/Primitive_string.cjs");
 let Belt_internalAVLtree = require("./Belt_internalAVLtree.cjs");
 
 function add(t, x, data) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalSetBuckets.cjs b/packages/@rescript/belt/lib/js/src/Belt_internalSetBuckets.cjs
similarity index 97%
rename from packages/@rescript/runtime/lib/js/Belt_internalSetBuckets.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_internalSetBuckets.cjs
index f79b21826e9..2c13e6c816a 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalSetBuckets.cjs
+++ b/packages/@rescript/belt/lib/js/src/Belt_internalSetBuckets.cjs
@@ -1,7 +1,7 @@
 'use strict';
 
 let Belt_Array = require("./Belt_Array.cjs");
-let Primitive_int = require("./Primitive_int.cjs");
+let Primitive_int = require("@rescript/runtime/lib/js/Primitive_int.cjs");
 
 function copyAuxCont(_c, _prec) {
   while (true) {
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalSetInt.cjs b/packages/@rescript/belt/lib/js/src/Belt_internalSetInt.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_internalSetInt.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_internalSetInt.cjs
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalSetString.cjs b/packages/@rescript/belt/lib/js/src/Belt_internalSetString.cjs
similarity index 100%
rename from packages/@rescript/runtime/lib/js/Belt_internalSetString.cjs
rename to packages/@rescript/belt/lib/js/src/Belt_internalSetString.cjs
diff --git a/packages/@rescript/belt/package.json b/packages/@rescript/belt/package.json
new file mode 100644
index 00000000000..e12d49333ac
--- /dev/null
+++ b/packages/@rescript/belt/package.json
@@ -0,0 +1,53 @@
+{
+  "name": "@rescript/belt",
+  "version": "13.0.0-alpha.6",
+  "description": "Extended utility and collection library for ReScript",
+  "license": "MIT",
+  "homepage": "https://rescript-lang.org",
+  "bugs": "https://github.com/rescript-lang/rescript/issues",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/rescript-lang/rescript.git"
+  },
+  "author": {
+    "name": "Hongbo Zhang",
+    "email": "bobzhang1988@gmail.com"
+  },
+  "maintainers": [
+    "Christoph Knittel (https://github.com/cknitt)",
+    "Cristiano Calcagno (https://github.com/cristianoc)",
+    "Dmitry Zakharov (https://github.com/DZakh)",
+    "Florian Hammerschmidt (https://github.com/fhammerschmidt)",
+    "Gabriel Nordeborn (https://github.com/zth)",
+    "Hyeseong Kim (https://github.com/cometkim)",
+    "Jaap Frolich (https://github.com/jfrolich)",
+    "Matthias Le Brun (https://github.com/bloodyowl)",
+    "Patrick Ecker (https://github.com/ryyppy)",
+    "Paul Tsnobiladzé (https://github.com/tsnobip)",
+    "Shulhi Sapli (https://github.com/shulhi)",
+    "Woonki Moon (https://github.com/mununki)"
+  ],
+  "publishConfig": {
+    "access": "public",
+    "provenance": true
+  },
+  "files": [
+    "README.md",
+    "rescript.json",
+    "src/**/*.res",
+    "src/**/*.resi"
+  ],
+  "scripts": {
+    "clean": "rescript clean",
+    "build": "rescript build && touch .buildstamp"
+  },
+  "peerDependencies": {
+    "@rescript/runtime": "workspace:^",
+    "rescript": "workspace:^"
+  },
+  "devDependencies": {
+    "@rescript/runtime": "workspace:^",
+    "rescript": "workspace:^"
+  },
+  "preferUnplugged": true
+}
diff --git a/packages/@rescript/belt/rescript.json b/packages/@rescript/belt/rescript.json
new file mode 100644
index 00000000000..791e43cd349
--- /dev/null
+++ b/packages/@rescript/belt/rescript.json
@@ -0,0 +1,30 @@
+{
+  "name": "@rescript/belt",
+  "sources": [
+    {
+      "dir": "src"
+    }
+  ],
+  "package-specs": [
+    {
+      "module": "commonjs",
+      "suffix": ".cjs",
+      "in-source": false
+    },
+    {
+      "module": "esmodule",
+      "suffix": ".mjs",
+      "in-source": false
+    }
+  ],
+  "compiler-flags": [
+    "-no-keep-locs",
+    "-no-alias-deps",
+    "-bs-no-version-header",
+    "-bs-no-check-div-by-zero",
+    "-bs-cross-module-opt",
+    "-unsafe",
+    "-w -3+50",
+    "-warn-error A"
+  ]
+}
diff --git a/packages/@rescript/runtime/Belt.res b/packages/@rescript/belt/src/Belt.res
similarity index 97%
rename from packages/@rescript/runtime/Belt.res
rename to packages/@rescript/belt/src/Belt.res
index 4b59fcb5094..4ac7fdf76da 100644
--- a/packages/@rescript/runtime/Belt.res
+++ b/packages/@rescript/belt/src/Belt.res
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: MIT
  */
 
-/*** The ReScript standard library.
+/*** Collection utilities for ReScript.
 
 Belt mostly covers collection types. Use the top-level `String` and `Date` modules for string and date functions.
 
@@ -20,6 +20,14 @@ Belt provides:
 
 ## Usage
 
+Install `@rescript/belt`, then add it to your project's `rescript.json`:
+
+```json
+{
+  "dependencies": ["@rescript/belt"]
+}
+```
+
 To use modules from Belt, either refer to them by their fully qualified name (`Belt.List`, `Belt.Array` etc.) or open the `Belt` module by putting
 
 ## Examples
diff --git a/packages/@rescript/runtime/Belt_Array.res b/packages/@rescript/belt/src/Belt_Array.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_Array.res
rename to packages/@rescript/belt/src/Belt_Array.res
diff --git a/packages/@rescript/runtime/Belt_Array.resi b/packages/@rescript/belt/src/Belt_Array.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_Array.resi
rename to packages/@rescript/belt/src/Belt_Array.resi
diff --git a/packages/@rescript/runtime/Belt_Float.res b/packages/@rescript/belt/src/Belt_Float.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_Float.res
rename to packages/@rescript/belt/src/Belt_Float.res
diff --git a/packages/@rescript/runtime/Belt_Float.resi b/packages/@rescript/belt/src/Belt_Float.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_Float.resi
rename to packages/@rescript/belt/src/Belt_Float.resi
diff --git a/packages/@rescript/runtime/Belt_HashMap.res b/packages/@rescript/belt/src/Belt_HashMap.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashMap.res
rename to packages/@rescript/belt/src/Belt_HashMap.res
diff --git a/packages/@rescript/runtime/Belt_HashMap.resi b/packages/@rescript/belt/src/Belt_HashMap.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashMap.resi
rename to packages/@rescript/belt/src/Belt_HashMap.resi
diff --git a/packages/@rescript/runtime/Belt_HashMapInt.res b/packages/@rescript/belt/src/Belt_HashMapInt.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashMapInt.res
rename to packages/@rescript/belt/src/Belt_HashMapInt.res
diff --git a/packages/@rescript/runtime/Belt_HashMapInt.resi b/packages/@rescript/belt/src/Belt_HashMapInt.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashMapInt.resi
rename to packages/@rescript/belt/src/Belt_HashMapInt.resi
diff --git a/packages/@rescript/runtime/Belt_HashMapString.res b/packages/@rescript/belt/src/Belt_HashMapString.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashMapString.res
rename to packages/@rescript/belt/src/Belt_HashMapString.res
diff --git a/packages/@rescript/runtime/Belt_HashMapString.resi b/packages/@rescript/belt/src/Belt_HashMapString.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashMapString.resi
rename to packages/@rescript/belt/src/Belt_HashMapString.resi
diff --git a/packages/@rescript/runtime/Belt_HashSet.res b/packages/@rescript/belt/src/Belt_HashSet.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashSet.res
rename to packages/@rescript/belt/src/Belt_HashSet.res
diff --git a/packages/@rescript/runtime/Belt_HashSet.resi b/packages/@rescript/belt/src/Belt_HashSet.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashSet.resi
rename to packages/@rescript/belt/src/Belt_HashSet.resi
diff --git a/packages/@rescript/runtime/Belt_HashSetInt.res b/packages/@rescript/belt/src/Belt_HashSetInt.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashSetInt.res
rename to packages/@rescript/belt/src/Belt_HashSetInt.res
diff --git a/packages/@rescript/runtime/Belt_HashSetInt.resi b/packages/@rescript/belt/src/Belt_HashSetInt.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashSetInt.resi
rename to packages/@rescript/belt/src/Belt_HashSetInt.resi
diff --git a/packages/@rescript/runtime/Belt_HashSetString.res b/packages/@rescript/belt/src/Belt_HashSetString.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashSetString.res
rename to packages/@rescript/belt/src/Belt_HashSetString.res
diff --git a/packages/@rescript/runtime/Belt_HashSetString.resi b/packages/@rescript/belt/src/Belt_HashSetString.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_HashSetString.resi
rename to packages/@rescript/belt/src/Belt_HashSetString.resi
diff --git a/packages/@rescript/runtime/Belt_Id.res b/packages/@rescript/belt/src/Belt_Id.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_Id.res
rename to packages/@rescript/belt/src/Belt_Id.res
diff --git a/packages/@rescript/runtime/Belt_Id.resi b/packages/@rescript/belt/src/Belt_Id.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_Id.resi
rename to packages/@rescript/belt/src/Belt_Id.resi
diff --git a/packages/@rescript/runtime/Belt_Int.res b/packages/@rescript/belt/src/Belt_Int.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_Int.res
rename to packages/@rescript/belt/src/Belt_Int.res
diff --git a/packages/@rescript/runtime/Belt_Int.resi b/packages/@rescript/belt/src/Belt_Int.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_Int.resi
rename to packages/@rescript/belt/src/Belt_Int.resi
diff --git a/packages/@rescript/runtime/Belt_List.res b/packages/@rescript/belt/src/Belt_List.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_List.res
rename to packages/@rescript/belt/src/Belt_List.res
diff --git a/packages/@rescript/runtime/Belt_List.resi b/packages/@rescript/belt/src/Belt_List.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_List.resi
rename to packages/@rescript/belt/src/Belt_List.resi
diff --git a/packages/@rescript/runtime/Belt_Map.res b/packages/@rescript/belt/src/Belt_Map.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_Map.res
rename to packages/@rescript/belt/src/Belt_Map.res
diff --git a/packages/@rescript/runtime/Belt_Map.resi b/packages/@rescript/belt/src/Belt_Map.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_Map.resi
rename to packages/@rescript/belt/src/Belt_Map.resi
diff --git a/packages/@rescript/runtime/Belt_MapDict.res b/packages/@rescript/belt/src/Belt_MapDict.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MapDict.res
rename to packages/@rescript/belt/src/Belt_MapDict.res
diff --git a/packages/@rescript/runtime/Belt_MapDict.resi b/packages/@rescript/belt/src/Belt_MapDict.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MapDict.resi
rename to packages/@rescript/belt/src/Belt_MapDict.resi
diff --git a/packages/@rescript/runtime/Belt_MapInt.res b/packages/@rescript/belt/src/Belt_MapInt.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MapInt.res
rename to packages/@rescript/belt/src/Belt_MapInt.res
diff --git a/packages/@rescript/runtime/Belt_MapInt.resi b/packages/@rescript/belt/src/Belt_MapInt.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MapInt.resi
rename to packages/@rescript/belt/src/Belt_MapInt.resi
diff --git a/packages/@rescript/runtime/Belt_MapString.res b/packages/@rescript/belt/src/Belt_MapString.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MapString.res
rename to packages/@rescript/belt/src/Belt_MapString.res
diff --git a/packages/@rescript/runtime/Belt_MapString.resi b/packages/@rescript/belt/src/Belt_MapString.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MapString.resi
rename to packages/@rescript/belt/src/Belt_MapString.resi
diff --git a/packages/@rescript/runtime/Belt_MutableMap.res b/packages/@rescript/belt/src/Belt_MutableMap.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableMap.res
rename to packages/@rescript/belt/src/Belt_MutableMap.res
diff --git a/packages/@rescript/runtime/Belt_MutableMap.resi b/packages/@rescript/belt/src/Belt_MutableMap.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableMap.resi
rename to packages/@rescript/belt/src/Belt_MutableMap.resi
diff --git a/packages/@rescript/runtime/Belt_MutableMapInt.res b/packages/@rescript/belt/src/Belt_MutableMapInt.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableMapInt.res
rename to packages/@rescript/belt/src/Belt_MutableMapInt.res
diff --git a/packages/@rescript/runtime/Belt_MutableMapInt.resi b/packages/@rescript/belt/src/Belt_MutableMapInt.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableMapInt.resi
rename to packages/@rescript/belt/src/Belt_MutableMapInt.resi
diff --git a/packages/@rescript/runtime/Belt_MutableMapString.res b/packages/@rescript/belt/src/Belt_MutableMapString.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableMapString.res
rename to packages/@rescript/belt/src/Belt_MutableMapString.res
diff --git a/packages/@rescript/runtime/Belt_MutableMapString.resi b/packages/@rescript/belt/src/Belt_MutableMapString.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableMapString.resi
rename to packages/@rescript/belt/src/Belt_MutableMapString.resi
diff --git a/packages/@rescript/runtime/Belt_MutableQueue.res b/packages/@rescript/belt/src/Belt_MutableQueue.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableQueue.res
rename to packages/@rescript/belt/src/Belt_MutableQueue.res
diff --git a/packages/@rescript/runtime/Belt_MutableQueue.resi b/packages/@rescript/belt/src/Belt_MutableQueue.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableQueue.resi
rename to packages/@rescript/belt/src/Belt_MutableQueue.resi
diff --git a/packages/@rescript/runtime/Belt_MutableSet.res b/packages/@rescript/belt/src/Belt_MutableSet.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableSet.res
rename to packages/@rescript/belt/src/Belt_MutableSet.res
diff --git a/packages/@rescript/runtime/Belt_MutableSet.resi b/packages/@rescript/belt/src/Belt_MutableSet.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableSet.resi
rename to packages/@rescript/belt/src/Belt_MutableSet.resi
diff --git a/packages/@rescript/runtime/Belt_MutableSetInt.res b/packages/@rescript/belt/src/Belt_MutableSetInt.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableSetInt.res
rename to packages/@rescript/belt/src/Belt_MutableSetInt.res
diff --git a/packages/@rescript/runtime/Belt_MutableSetInt.resi b/packages/@rescript/belt/src/Belt_MutableSetInt.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableSetInt.resi
rename to packages/@rescript/belt/src/Belt_MutableSetInt.resi
diff --git a/packages/@rescript/runtime/Belt_MutableSetString.res b/packages/@rescript/belt/src/Belt_MutableSetString.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableSetString.res
rename to packages/@rescript/belt/src/Belt_MutableSetString.res
diff --git a/packages/@rescript/runtime/Belt_MutableSetString.resi b/packages/@rescript/belt/src/Belt_MutableSetString.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableSetString.resi
rename to packages/@rescript/belt/src/Belt_MutableSetString.resi
diff --git a/packages/@rescript/runtime/Belt_MutableStack.res b/packages/@rescript/belt/src/Belt_MutableStack.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableStack.res
rename to packages/@rescript/belt/src/Belt_MutableStack.res
diff --git a/packages/@rescript/runtime/Belt_MutableStack.resi b/packages/@rescript/belt/src/Belt_MutableStack.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_MutableStack.resi
rename to packages/@rescript/belt/src/Belt_MutableStack.resi
diff --git a/packages/@rescript/runtime/Belt_Option.res b/packages/@rescript/belt/src/Belt_Option.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_Option.res
rename to packages/@rescript/belt/src/Belt_Option.res
diff --git a/packages/@rescript/runtime/Belt_Option.resi b/packages/@rescript/belt/src/Belt_Option.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_Option.resi
rename to packages/@rescript/belt/src/Belt_Option.resi
diff --git a/packages/@rescript/runtime/Belt_Range.res b/packages/@rescript/belt/src/Belt_Range.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_Range.res
rename to packages/@rescript/belt/src/Belt_Range.res
diff --git a/packages/@rescript/runtime/Belt_Range.resi b/packages/@rescript/belt/src/Belt_Range.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_Range.resi
rename to packages/@rescript/belt/src/Belt_Range.resi
diff --git a/packages/@rescript/runtime/Belt_Result.res b/packages/@rescript/belt/src/Belt_Result.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_Result.res
rename to packages/@rescript/belt/src/Belt_Result.res
diff --git a/packages/@rescript/runtime/Belt_Result.resi b/packages/@rescript/belt/src/Belt_Result.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_Result.resi
rename to packages/@rescript/belt/src/Belt_Result.resi
diff --git a/packages/@rescript/runtime/Belt_Set.res b/packages/@rescript/belt/src/Belt_Set.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_Set.res
rename to packages/@rescript/belt/src/Belt_Set.res
diff --git a/packages/@rescript/runtime/Belt_Set.resi b/packages/@rescript/belt/src/Belt_Set.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_Set.resi
rename to packages/@rescript/belt/src/Belt_Set.resi
diff --git a/packages/@rescript/runtime/Belt_SetDict.res b/packages/@rescript/belt/src/Belt_SetDict.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_SetDict.res
rename to packages/@rescript/belt/src/Belt_SetDict.res
diff --git a/packages/@rescript/runtime/Belt_SetDict.resi b/packages/@rescript/belt/src/Belt_SetDict.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_SetDict.resi
rename to packages/@rescript/belt/src/Belt_SetDict.resi
diff --git a/packages/@rescript/runtime/Belt_SetInt.res b/packages/@rescript/belt/src/Belt_SetInt.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_SetInt.res
rename to packages/@rescript/belt/src/Belt_SetInt.res
diff --git a/packages/@rescript/runtime/Belt_SetInt.resi b/packages/@rescript/belt/src/Belt_SetInt.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_SetInt.resi
rename to packages/@rescript/belt/src/Belt_SetInt.resi
diff --git a/packages/@rescript/runtime/Belt_SetString.res b/packages/@rescript/belt/src/Belt_SetString.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_SetString.res
rename to packages/@rescript/belt/src/Belt_SetString.res
diff --git a/packages/@rescript/runtime/Belt_SetString.resi b/packages/@rescript/belt/src/Belt_SetString.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_SetString.resi
rename to packages/@rescript/belt/src/Belt_SetString.resi
diff --git a/packages/@rescript/runtime/Belt_SortArray.res b/packages/@rescript/belt/src/Belt_SortArray.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_SortArray.res
rename to packages/@rescript/belt/src/Belt_SortArray.res
diff --git a/packages/@rescript/runtime/Belt_SortArray.resi b/packages/@rescript/belt/src/Belt_SortArray.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_SortArray.resi
rename to packages/@rescript/belt/src/Belt_SortArray.resi
diff --git a/packages/@rescript/runtime/Belt_SortArrayInt.res b/packages/@rescript/belt/src/Belt_SortArrayInt.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_SortArrayInt.res
rename to packages/@rescript/belt/src/Belt_SortArrayInt.res
diff --git a/packages/@rescript/runtime/Belt_SortArrayInt.resi b/packages/@rescript/belt/src/Belt_SortArrayInt.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_SortArrayInt.resi
rename to packages/@rescript/belt/src/Belt_SortArrayInt.resi
diff --git a/packages/@rescript/runtime/Belt_SortArrayString.res b/packages/@rescript/belt/src/Belt_SortArrayString.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_SortArrayString.res
rename to packages/@rescript/belt/src/Belt_SortArrayString.res
diff --git a/packages/@rescript/runtime/Belt_SortArrayString.resi b/packages/@rescript/belt/src/Belt_SortArrayString.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_SortArrayString.resi
rename to packages/@rescript/belt/src/Belt_SortArrayString.resi
diff --git a/packages/@rescript/runtime/Belt_internalAVLset.res b/packages/@rescript/belt/src/Belt_internalAVLset.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalAVLset.res
rename to packages/@rescript/belt/src/Belt_internalAVLset.res
diff --git a/packages/@rescript/runtime/Belt_internalAVLset.resi b/packages/@rescript/belt/src/Belt_internalAVLset.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalAVLset.resi
rename to packages/@rescript/belt/src/Belt_internalAVLset.resi
diff --git a/packages/@rescript/runtime/Belt_internalAVLtree.res b/packages/@rescript/belt/src/Belt_internalAVLtree.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalAVLtree.res
rename to packages/@rescript/belt/src/Belt_internalAVLtree.res
diff --git a/packages/@rescript/runtime/Belt_internalAVLtree.resi b/packages/@rescript/belt/src/Belt_internalAVLtree.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalAVLtree.resi
rename to packages/@rescript/belt/src/Belt_internalAVLtree.resi
diff --git a/packages/@rescript/runtime/Belt_internalBuckets.res b/packages/@rescript/belt/src/Belt_internalBuckets.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalBuckets.res
rename to packages/@rescript/belt/src/Belt_internalBuckets.res
diff --git a/packages/@rescript/runtime/Belt_internalBuckets.resi b/packages/@rescript/belt/src/Belt_internalBuckets.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalBuckets.resi
rename to packages/@rescript/belt/src/Belt_internalBuckets.resi
diff --git a/packages/@rescript/runtime/Belt_internalBucketsType.res b/packages/@rescript/belt/src/Belt_internalBucketsType.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalBucketsType.res
rename to packages/@rescript/belt/src/Belt_internalBucketsType.res
diff --git a/packages/@rescript/runtime/Belt_internalBucketsType.resi b/packages/@rescript/belt/src/Belt_internalBucketsType.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalBucketsType.resi
rename to packages/@rescript/belt/src/Belt_internalBucketsType.resi
diff --git a/packages/@rescript/runtime/Belt_internalMapInt.res b/packages/@rescript/belt/src/Belt_internalMapInt.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalMapInt.res
rename to packages/@rescript/belt/src/Belt_internalMapInt.res
diff --git a/packages/@rescript/runtime/Belt_internalMapString.res b/packages/@rescript/belt/src/Belt_internalMapString.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalMapString.res
rename to packages/@rescript/belt/src/Belt_internalMapString.res
diff --git a/packages/@rescript/runtime/Belt_internalSetBuckets.res b/packages/@rescript/belt/src/Belt_internalSetBuckets.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalSetBuckets.res
rename to packages/@rescript/belt/src/Belt_internalSetBuckets.res
diff --git a/packages/@rescript/runtime/Belt_internalSetBuckets.resi b/packages/@rescript/belt/src/Belt_internalSetBuckets.resi
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalSetBuckets.resi
rename to packages/@rescript/belt/src/Belt_internalSetBuckets.resi
diff --git a/packages/@rescript/runtime/Belt_internalSetInt.res b/packages/@rescript/belt/src/Belt_internalSetInt.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalSetInt.res
rename to packages/@rescript/belt/src/Belt_internalSetInt.res
diff --git a/packages/@rescript/runtime/Belt_internalSetString.res b/packages/@rescript/belt/src/Belt_internalSetString.res
similarity index 100%
rename from packages/@rescript/runtime/Belt_internalSetString.res
rename to packages/@rescript/belt/src/Belt_internalSetString.res
diff --git a/packages/@rescript/runtime/Primitive_array.res b/packages/@rescript/runtime/Primitive_array.res
index 6a7d994d4de..7bfef9b575d 100644
--- a/packages/@rescript/runtime/Primitive_array.res
+++ b/packages/@rescript/runtime/Primitive_array.res
@@ -13,3 +13,30 @@ let set = (xs, index, newval) =>
   } else {
     xs->Primitive_array_extern.setUnsafe(index, newval)
   }
+
+// Note: this is exposed to support syntax
+@new external makeUninitializedUnsafe: int => array<'a> = "Array"
+
+let spread = arrays => {
+  let arraysLength = length(arrays)
+  let resultLength = ref(0)
+  for i in 0 to arraysLength - 1 {
+    resultLength.contents =
+      resultLength.contents + length(Primitive_array_extern.getUnsafe(arrays, i))
+  }
+
+  let result = makeUninitializedUnsafe(resultLength.contents)
+  resultLength.contents = 0
+  for i in 0 to arraysLength - 1 {
+    let array = Primitive_array_extern.getUnsafe(arrays, i)
+    for j in 0 to length(array) - 1 {
+      Primitive_array_extern.setUnsafe(
+        result,
+        resultLength.contents,
+        Primitive_array_extern.getUnsafe(array, j),
+      )
+      resultLength.contents = resultLength.contents + 1
+    }
+  }
+  result
+}
diff --git a/packages/@rescript/runtime/Primitive_list.res b/packages/@rescript/runtime/Primitive_list.res
new file mode 100644
index 00000000000..9eeb7c75eb3
--- /dev/null
+++ b/packages/@rescript/runtime/Primitive_list.res
@@ -0,0 +1,35 @@
+// Note: this is exposed to support syntax
+external mutableCell: ('a, list<'a>) => list<'a> = "#makemutablelist"
+
+@set external unsafeMutateTail: (list<'a>, list<'a>) => unit = "tl"
+
+let rec copyAux = (list, previous) =>
+  switch list {
+  | list{} => previous
+  | list{head, ...tail} =>
+    let next = mutableCell(head, list{})
+    unsafeMutateTail(previous, next)
+    copyAux(tail, next)
+  }
+
+let concat = (left, right) =>
+  switch left {
+  | list{} => right
+  | list{head, ...tail} =>
+    let result = mutableCell(head, list{})
+    unsafeMutateTail(copyAux(tail, result), right)
+    result
+  }
+
+let spread = lists =>
+  switch lists {
+  | [] => list{}
+  | [list] => list
+  | _ =>
+    let length = Primitive_array_extern.length(lists)
+    let result = ref(Primitive_array_extern.getUnsafe(lists, length - 1))
+    for i in length - 2 downto 0 {
+      result.contents = concat(Primitive_array_extern.getUnsafe(lists, i), result.contents)
+    }
+    result.contents
+  }
diff --git a/packages/@rescript/runtime/Primitive_list.resi b/packages/@rescript/runtime/Primitive_list.resi
new file mode 100644
index 00000000000..0ab7bf2d8c0
--- /dev/null
+++ b/packages/@rescript/runtime/Primitive_list.resi
@@ -0,0 +1,2 @@
+// Note: this is exposed to support syntax
+let spread: array<list<'a>> => list<'a>
diff --git a/packages/@rescript/runtime/Stdlib_Map.resi b/packages/@rescript/runtime/Stdlib_Map.resi
index f0930383dc4..28975651ee1 100644
--- a/packages/@rescript/runtime/Stdlib_Map.resi
+++ b/packages/@rescript/runtime/Stdlib_Map.resi
@@ -34,7 +34,8 @@ map->Map.set("lang", "ReScript") // Inferred as Map.t<string, string>
 ```
 
 ## Alternatives
-A JavaScript `Map` is mutable. If you're looking for an immutable alternative, check out`Belt.Map`.
+A JavaScript `Map` is mutable. For an immutable alternative, install the separate
+`@rescript/belt` package and check out `Belt.Map`.
 */
 @new
 external make: unit => t<'k, 'v> = "Map"
diff --git a/packages/@rescript/runtime/Stdlib_Set.resi b/packages/@rescript/runtime/Stdlib_Set.resi
index 497070c1240..8d32617608f 100644
--- a/packages/@rescript/runtime/Stdlib_Set.resi
+++ b/packages/@rescript/runtime/Stdlib_Set.resi
@@ -33,7 +33,8 @@ set->Set.add("Fine name") // Inferred as Set.t<string>
 ```
 
 ## Alternatives
-A JavaScript `Set` is mutable. If you're looking for an immutable alternative, check out `Belt.Set`.
+A JavaScript `Set` is mutable. For an immutable alternative, install the separate
+`@rescript/belt` package and check out `Belt.Set`.
 */
 @new
 external make: unit => t<'a> = "Set"
diff --git a/packages/@rescript/runtime/lib/es6/Primitive_array.mjs b/packages/@rescript/runtime/lib/es6/Primitive_array.mjs
index 61e5492a8ba..b85c60c3237 100644
--- a/packages/@rescript/runtime/lib/es6/Primitive_array.mjs
+++ b/packages/@rescript/runtime/lib/es6/Primitive_array.mjs
@@ -27,9 +27,28 @@ function set(xs, index, newval) {
   xs[index] = newval;
 }
 
+function spread(arrays) {
+  let arraysLength = arrays.length;
+  let resultLength = 0;
+  for (let i = 0; i < arraysLength; ++i) {
+    resultLength = resultLength + arrays[i].length | 0;
+  }
+  let result = new Array(resultLength);
+  resultLength = 0;
+  for (let i$1 = 0; i$1 < arraysLength; ++i$1) {
+    let array = arrays[i$1];
+    for (let j = 0, j_finish = array.length; j < j_finish; ++j) {
+      result[resultLength] = array[j];
+      resultLength = resultLength + 1 | 0;
+    }
+  }
+  return result;
+}
+
 export {
   length,
   get,
   set,
+  spread,
 }
 /* No side effect */
diff --git a/packages/@rescript/runtime/lib/es6/Primitive_list.mjs b/packages/@rescript/runtime/lib/es6/Primitive_list.mjs
new file mode 100644
index 00000000000..53ae38b0aab
--- /dev/null
+++ b/packages/@rescript/runtime/lib/es6/Primitive_list.mjs
@@ -0,0 +1,53 @@
+
+
+
+function copyAux(_list, _previous) {
+  while (true) {
+    let previous = _previous;
+    let list = _list;
+    if (list === 0) {
+      return previous;
+    }
+    let next = {
+      hd: list.hd,
+      tl: /* [] */0
+    };
+    previous.tl = next;
+    _previous = next;
+    _list = list.tl;
+    continue;
+  };
+}
+
+function concat(left, right) {
+  if (left === 0) {
+    return right;
+  }
+  let result = {
+    hd: left.hd,
+    tl: /* [] */0
+  };
+  copyAux(left.tl, result).tl = right;
+  return result;
+}
+
+function spread(lists) {
+  let len = lists.length;
+  if (len === 1) {
+    return lists[0];
+  }
+  if (len === 0) {
+    return /* [] */0;
+  }
+  let length = lists.length;
+  let result = lists[length - 1 | 0];
+  for (let i = length - 2 | 0; i >= 0; --i) {
+    result = concat(lists[i], result);
+  }
+  return result;
+}
+
+export {
+  spread,
+}
+/* No side effect */
diff --git a/packages/@rescript/runtime/lib/js/Primitive_array.cjs b/packages/@rescript/runtime/lib/js/Primitive_array.cjs
index 7bd0ed82576..d4eeabe9f77 100644
--- a/packages/@rescript/runtime/lib/js/Primitive_array.cjs
+++ b/packages/@rescript/runtime/lib/js/Primitive_array.cjs
@@ -27,7 +27,26 @@ function set(xs, index, newval) {
   xs[index] = newval;
 }
 
+function spread(arrays) {
+  let arraysLength = arrays.length;
+  let resultLength = 0;
+  for (let i = 0; i < arraysLength; ++i) {
+    resultLength = resultLength + arrays[i].length | 0;
+  }
+  let result = new Array(resultLength);
+  resultLength = 0;
+  for (let i$1 = 0; i$1 < arraysLength; ++i$1) {
+    let array = arrays[i$1];
+    for (let j = 0, j_finish = array.length; j < j_finish; ++j) {
+      result[resultLength] = array[j];
+      resultLength = resultLength + 1 | 0;
+    }
+  }
+  return result;
+}
+
 exports.length = length;
 exports.get = get;
 exports.set = set;
+exports.spread = spread;
 /* No side effect */
diff --git a/packages/@rescript/runtime/lib/js/Primitive_list.cjs b/packages/@rescript/runtime/lib/js/Primitive_list.cjs
new file mode 100644
index 00000000000..4b184399789
--- /dev/null
+++ b/packages/@rescript/runtime/lib/js/Primitive_list.cjs
@@ -0,0 +1,51 @@
+'use strict';
+
+
+function copyAux(_list, _previous) {
+  while (true) {
+    let previous = _previous;
+    let list = _list;
+    if (list === 0) {
+      return previous;
+    }
+    let next = {
+      hd: list.hd,
+      tl: /* [] */0
+    };
+    previous.tl = next;
+    _previous = next;
+    _list = list.tl;
+    continue;
+  };
+}
+
+function concat(left, right) {
+  if (left === 0) {
+    return right;
+  }
+  let result = {
+    hd: left.hd,
+    tl: /* [] */0
+  };
+  copyAux(left.tl, result).tl = right;
+  return result;
+}
+
+function spread(lists) {
+  let len = lists.length;
+  if (len === 1) {
+    return lists[0];
+  }
+  if (len === 0) {
+    return /* [] */0;
+  }
+  let length = lists.length;
+  let result = lists[length - 1 | 0];
+  for (let i = length - 2 | 0; i >= 0; --i) {
+    result = concat(lists[i], result);
+  }
+  return result;
+}
+
+exports.spread = spread;
+/* No side effect */
diff --git a/packages/artifacts.json b/packages/artifacts.json
index 1158b170112..135b8da7f6b 100644
--- a/packages/artifacts.json
+++ b/packages/artifacts.json
@@ -18,49 +18,6 @@
     "package.json"
   ],
   "@rescript/runtime": [
-    "lib/es6/Belt.mjs",
-    "lib/es6/Belt_Array.mjs",
-    "lib/es6/Belt_Float.mjs",
-    "lib/es6/Belt_HashMap.mjs",
-    "lib/es6/Belt_HashMapInt.mjs",
-    "lib/es6/Belt_HashMapString.mjs",
-    "lib/es6/Belt_HashSet.mjs",
-    "lib/es6/Belt_HashSetInt.mjs",
-    "lib/es6/Belt_HashSetString.mjs",
-    "lib/es6/Belt_Id.mjs",
-    "lib/es6/Belt_Int.mjs",
-    "lib/es6/Belt_List.mjs",
-    "lib/es6/Belt_Map.mjs",
-    "lib/es6/Belt_MapDict.mjs",
-    "lib/es6/Belt_MapInt.mjs",
-    "lib/es6/Belt_MapString.mjs",
-    "lib/es6/Belt_MutableMap.mjs",
-    "lib/es6/Belt_MutableMapInt.mjs",
-    "lib/es6/Belt_MutableMapString.mjs",
-    "lib/es6/Belt_MutableQueue.mjs",
-    "lib/es6/Belt_MutableSet.mjs",
-    "lib/es6/Belt_MutableSetInt.mjs",
-    "lib/es6/Belt_MutableSetString.mjs",
-    "lib/es6/Belt_MutableStack.mjs",
-    "lib/es6/Belt_Option.mjs",
-    "lib/es6/Belt_Range.mjs",
-    "lib/es6/Belt_Result.mjs",
-    "lib/es6/Belt_Set.mjs",
-    "lib/es6/Belt_SetDict.mjs",
-    "lib/es6/Belt_SetInt.mjs",
-    "lib/es6/Belt_SetString.mjs",
-    "lib/es6/Belt_SortArray.mjs",
-    "lib/es6/Belt_SortArrayInt.mjs",
-    "lib/es6/Belt_SortArrayString.mjs",
-    "lib/es6/Belt_internalAVLset.mjs",
-    "lib/es6/Belt_internalAVLtree.mjs",
-    "lib/es6/Belt_internalBuckets.mjs",
-    "lib/es6/Belt_internalBucketsType.mjs",
-    "lib/es6/Belt_internalMapInt.mjs",
-    "lib/es6/Belt_internalMapString.mjs",
-    "lib/es6/Belt_internalSetBuckets.mjs",
-    "lib/es6/Belt_internalSetInt.mjs",
-    "lib/es6/Belt_internalSetString.mjs",
     "lib/es6/Char.mjs",
     "lib/es6/Dom.mjs",
     "lib/es6/Dom_storage.mjs",
@@ -85,6 +42,7 @@
     "lib/es6/Primitive_int.mjs",
     "lib/es6/Primitive_int_extern.mjs",
     "lib/es6/Primitive_js_extern.mjs",
+    "lib/es6/Primitive_list.mjs",
     "lib/es6/Primitive_module.mjs",
     "lib/es6/Primitive_object.mjs",
     "lib/es6/Primitive_object_extern.mjs",
@@ -168,49 +126,6 @@
     "lib/es6/Stdlib_Uint8ClampedArray.mjs",
     "lib/es6/Stdlib_WeakMap.mjs",
     "lib/es6/Stdlib_WeakSet.mjs",
-    "lib/js/Belt.cjs",
-    "lib/js/Belt_Array.cjs",
-    "lib/js/Belt_Float.cjs",
-    "lib/js/Belt_HashMap.cjs",
-    "lib/js/Belt_HashMapInt.cjs",
-    "lib/js/Belt_HashMapString.cjs",
-    "lib/js/Belt_HashSet.cjs",
-    "lib/js/Belt_HashSetInt.cjs",
-    "lib/js/Belt_HashSetString.cjs",
-    "lib/js/Belt_Id.cjs",
-    "lib/js/Belt_Int.cjs",
-    "lib/js/Belt_List.cjs",
-    "lib/js/Belt_Map.cjs",
-    "lib/js/Belt_MapDict.cjs",
-    "lib/js/Belt_MapInt.cjs",
-    "lib/js/Belt_MapString.cjs",
-    "lib/js/Belt_MutableMap.cjs",
-    "lib/js/Belt_MutableMapInt.cjs",
-    "lib/js/Belt_MutableMapString.cjs",
-    "lib/js/Belt_MutableQueue.cjs",
-    "lib/js/Belt_MutableSet.cjs",
-    "lib/js/Belt_MutableSetInt.cjs",
-    "lib/js/Belt_MutableSetString.cjs",
-    "lib/js/Belt_MutableStack.cjs",
-    "lib/js/Belt_Option.cjs",
-    "lib/js/Belt_Range.cjs",
-    "lib/js/Belt_Result.cjs",
-    "lib/js/Belt_Set.cjs",
-    "lib/js/Belt_SetDict.cjs",
-    "lib/js/Belt_SetInt.cjs",
-    "lib/js/Belt_SetString.cjs",
-    "lib/js/Belt_SortArray.cjs",
-    "lib/js/Belt_SortArrayInt.cjs",
-    "lib/js/Belt_SortArrayString.cjs",
-    "lib/js/Belt_internalAVLset.cjs",
-    "lib/js/Belt_internalAVLtree.cjs",
-    "lib/js/Belt_internalBuckets.cjs",
-    "lib/js/Belt_internalBucketsType.cjs",
-    "lib/js/Belt_internalMapInt.cjs",
-    "lib/js/Belt_internalMapString.cjs",
-    "lib/js/Belt_internalSetBuckets.cjs",
-    "lib/js/Belt_internalSetInt.cjs",
-    "lib/js/Belt_internalSetString.cjs",
     "lib/js/Char.cjs",
     "lib/js/Dom.cjs",
     "lib/js/Dom_storage.cjs",
@@ -235,6 +150,7 @@
     "lib/js/Primitive_int.cjs",
     "lib/js/Primitive_int_extern.cjs",
     "lib/js/Primitive_js_extern.cjs",
+    "lib/js/Primitive_list.cjs",
     "lib/js/Primitive_module.cjs",
     "lib/js/Primitive_object.cjs",
     "lib/js/Primitive_object_extern.cjs",
@@ -318,254 +234,6 @@
     "lib/js/Stdlib_Uint8ClampedArray.cjs",
     "lib/js/Stdlib_WeakMap.cjs",
     "lib/js/Stdlib_WeakSet.cjs",
-    "lib/ocaml/Belt.cmi",
-    "lib/ocaml/Belt.cmj",
-    "lib/ocaml/Belt.cmt",
-    "lib/ocaml/Belt.res",
-    "lib/ocaml/Belt_Array.cmi",
-    "lib/ocaml/Belt_Array.cmj",
-    "lib/ocaml/Belt_Array.cmt",
-    "lib/ocaml/Belt_Array.cmti",
-    "lib/ocaml/Belt_Array.res",
-    "lib/ocaml/Belt_Array.resi",
-    "lib/ocaml/Belt_Float.cmi",
-    "lib/ocaml/Belt_Float.cmj",
-    "lib/ocaml/Belt_Float.cmt",
-    "lib/ocaml/Belt_Float.cmti",
-    "lib/ocaml/Belt_Float.res",
-    "lib/ocaml/Belt_Float.resi",
-    "lib/ocaml/Belt_HashMap.cmi",
-    "lib/ocaml/Belt_HashMap.cmj",
-    "lib/ocaml/Belt_HashMap.cmt",
-    "lib/ocaml/Belt_HashMap.cmti",
-    "lib/ocaml/Belt_HashMap.res",
-    "lib/ocaml/Belt_HashMap.resi",
-    "lib/ocaml/Belt_HashMapInt.cmi",
-    "lib/ocaml/Belt_HashMapInt.cmj",
-    "lib/ocaml/Belt_HashMapInt.cmt",
-    "lib/ocaml/Belt_HashMapInt.cmti",
-    "lib/ocaml/Belt_HashMapInt.res",
-    "lib/ocaml/Belt_HashMapInt.resi",
-    "lib/ocaml/Belt_HashMapString.cmi",
-    "lib/ocaml/Belt_HashMapString.cmj",
-    "lib/ocaml/Belt_HashMapString.cmt",
-    "lib/ocaml/Belt_HashMapString.cmti",
-    "lib/ocaml/Belt_HashMapString.res",
-    "lib/ocaml/Belt_HashMapString.resi",
-    "lib/ocaml/Belt_HashSet.cmi",
-    "lib/ocaml/Belt_HashSet.cmj",
-    "lib/ocaml/Belt_HashSet.cmt",
-    "lib/ocaml/Belt_HashSet.cmti",
-    "lib/ocaml/Belt_HashSet.res",
-    "lib/ocaml/Belt_HashSet.resi",
-    "lib/ocaml/Belt_HashSetInt.cmi",
-    "lib/ocaml/Belt_HashSetInt.cmj",
-    "lib/ocaml/Belt_HashSetInt.cmt",
-    "lib/ocaml/Belt_HashSetInt.cmti",
-    "lib/ocaml/Belt_HashSetInt.res",
-    "lib/ocaml/Belt_HashSetInt.resi",
-    "lib/ocaml/Belt_HashSetString.cmi",
-    "lib/ocaml/Belt_HashSetString.cmj",
-    "lib/ocaml/Belt_HashSetString.cmt",
-    "lib/ocaml/Belt_HashSetString.cmti",
-    "lib/ocaml/Belt_HashSetString.res",
-    "lib/ocaml/Belt_HashSetString.resi",
-    "lib/ocaml/Belt_Id.cmi",
-    "lib/ocaml/Belt_Id.cmj",
-    "lib/ocaml/Belt_Id.cmt",
-    "lib/ocaml/Belt_Id.cmti",
-    "lib/ocaml/Belt_Id.res",
-    "lib/ocaml/Belt_Id.resi",
-    "lib/ocaml/Belt_Int.cmi",
-    "lib/ocaml/Belt_Int.cmj",
-    "lib/ocaml/Belt_Int.cmt",
-    "lib/ocaml/Belt_Int.cmti",
-    "lib/ocaml/Belt_Int.res",
-    "lib/ocaml/Belt_Int.resi",
-    "lib/ocaml/Belt_List.cmi",
-    "lib/ocaml/Belt_List.cmj",
-    "lib/ocaml/Belt_List.cmt",
-    "lib/ocaml/Belt_List.cmti",
-    "lib/ocaml/Belt_List.res",
-    "lib/ocaml/Belt_List.resi",
-    "lib/ocaml/Belt_Map.cmi",
-    "lib/ocaml/Belt_Map.cmj",
-    "lib/ocaml/Belt_Map.cmt",
-    "lib/ocaml/Belt_Map.cmti",
-    "lib/ocaml/Belt_Map.res",
-    "lib/ocaml/Belt_Map.resi",
-    "lib/ocaml/Belt_MapDict.cmi",
-    "lib/ocaml/Belt_MapDict.cmj",
-    "lib/ocaml/Belt_MapDict.cmt",
-    "lib/ocaml/Belt_MapDict.cmti",
-    "lib/ocaml/Belt_MapDict.res",
-    "lib/ocaml/Belt_MapDict.resi",
-    "lib/ocaml/Belt_MapInt.cmi",
-    "lib/ocaml/Belt_MapInt.cmj",
-    "lib/ocaml/Belt_MapInt.cmt",
-    "lib/ocaml/Belt_MapInt.cmti",
-    "lib/ocaml/Belt_MapInt.res",
-    "lib/ocaml/Belt_MapInt.resi",
-    "lib/ocaml/Belt_MapString.cmi",
-    "lib/ocaml/Belt_MapString.cmj",
-    "lib/ocaml/Belt_MapString.cmt",
-    "lib/ocaml/Belt_MapString.cmti",
-    "lib/ocaml/Belt_MapString.res",
-    "lib/ocaml/Belt_MapString.resi",
-    "lib/ocaml/Belt_MutableMap.cmi",
-    "lib/ocaml/Belt_MutableMap.cmj",
-    "lib/ocaml/Belt_MutableMap.cmt",
-    "lib/ocaml/Belt_MutableMap.cmti",
-    "lib/ocaml/Belt_MutableMap.res",
-    "lib/ocaml/Belt_MutableMap.resi",
-    "lib/ocaml/Belt_MutableMapInt.cmi",
-    "lib/ocaml/Belt_MutableMapInt.cmj",
-    "lib/ocaml/Belt_MutableMapInt.cmt",
-    "lib/ocaml/Belt_MutableMapInt.cmti",
-    "lib/ocaml/Belt_MutableMapInt.res",
-    "lib/ocaml/Belt_MutableMapInt.resi",
-    "lib/ocaml/Belt_MutableMapString.cmi",
-    "lib/ocaml/Belt_MutableMapString.cmj",
-    "lib/ocaml/Belt_MutableMapString.cmt",
-    "lib/ocaml/Belt_MutableMapString.cmti",
-    "lib/ocaml/Belt_MutableMapString.res",
-    "lib/ocaml/Belt_MutableMapString.resi",
-    "lib/ocaml/Belt_MutableQueue.cmi",
-    "lib/ocaml/Belt_MutableQueue.cmj",
-    "lib/ocaml/Belt_MutableQueue.cmt",
-    "lib/ocaml/Belt_MutableQueue.cmti",
-    "lib/ocaml/Belt_MutableQueue.res",
-    "lib/ocaml/Belt_MutableQueue.resi",
-    "lib/ocaml/Belt_MutableSet.cmi",
-    "lib/ocaml/Belt_MutableSet.cmj",
-    "lib/ocaml/Belt_MutableSet.cmt",
-    "lib/ocaml/Belt_MutableSet.cmti",
-    "lib/ocaml/Belt_MutableSet.res",
-    "lib/ocaml/Belt_MutableSet.resi",
-    "lib/ocaml/Belt_MutableSetInt.cmi",
-    "lib/ocaml/Belt_MutableSetInt.cmj",
-    "lib/ocaml/Belt_MutableSetInt.cmt",
-    "lib/ocaml/Belt_MutableSetInt.cmti",
-    "lib/ocaml/Belt_MutableSetInt.res",
-    "lib/ocaml/Belt_MutableSetInt.resi",
-    "lib/ocaml/Belt_MutableSetString.cmi",
-    "lib/ocaml/Belt_MutableSetString.cmj",
-    "lib/ocaml/Belt_MutableSetString.cmt",
-    "lib/ocaml/Belt_MutableSetString.cmti",
-    "lib/ocaml/Belt_MutableSetString.res",
-    "lib/ocaml/Belt_MutableSetString.resi",
-    "lib/ocaml/Belt_MutableStack.cmi",
-    "lib/ocaml/Belt_MutableStack.cmj",
-    "lib/ocaml/Belt_MutableStack.cmt",
-    "lib/ocaml/Belt_MutableStack.cmti",
-    "lib/ocaml/Belt_MutableStack.res",
-    "lib/ocaml/Belt_MutableStack.resi",
-    "lib/ocaml/Belt_Option.cmi",
-    "lib/ocaml/Belt_Option.cmj",
-    "lib/ocaml/Belt_Option.cmt",
-    "lib/ocaml/Belt_Option.cmti",
-    "lib/ocaml/Belt_Option.res",
-    "lib/ocaml/Belt_Option.resi",
-    "lib/ocaml/Belt_Range.cmi",
-    "lib/ocaml/Belt_Range.cmj",
-    "lib/ocaml/Belt_Range.cmt",
-    "lib/ocaml/Belt_Range.cmti",
-    "lib/ocaml/Belt_Range.res",
-    "lib/ocaml/Belt_Range.resi",
-    "lib/ocaml/Belt_Result.cmi",
-    "lib/ocaml/Belt_Result.cmj",
-    "lib/ocaml/Belt_Result.cmt",
-    "lib/ocaml/Belt_Result.cmti",
-    "lib/ocaml/Belt_Result.res",
-    "lib/ocaml/Belt_Result.resi",
-    "lib/ocaml/Belt_Set.cmi",
-    "lib/ocaml/Belt_Set.cmj",
-    "lib/ocaml/Belt_Set.cmt",
-    "lib/ocaml/Belt_Set.cmti",
-    "lib/ocaml/Belt_Set.res",
-    "lib/ocaml/Belt_Set.resi",
-    "lib/ocaml/Belt_SetDict.cmi",
-    "lib/ocaml/Belt_SetDict.cmj",
-    "lib/ocaml/Belt_SetDict.cmt",
-    "lib/ocaml/Belt_SetDict.cmti",
-    "lib/ocaml/Belt_SetDict.res",
-    "lib/ocaml/Belt_SetDict.resi",
-    "lib/ocaml/Belt_SetInt.cmi",
-    "lib/ocaml/Belt_SetInt.cmj",
-    "lib/ocaml/Belt_SetInt.cmt",
-    "lib/ocaml/Belt_SetInt.cmti",
-    "lib/ocaml/Belt_SetInt.res",
-    "lib/ocaml/Belt_SetInt.resi",
-    "lib/ocaml/Belt_SetString.cmi",
-    "lib/ocaml/Belt_SetString.cmj",
-    "lib/ocaml/Belt_SetString.cmt",
-    "lib/ocaml/Belt_SetString.cmti",
-    "lib/ocaml/Belt_SetString.res",
-    "lib/ocaml/Belt_SetString.resi",
-    "lib/ocaml/Belt_SortArray.cmi",
-    "lib/ocaml/Belt_SortArray.cmj",
-    "lib/ocaml/Belt_SortArray.cmt",
-    "lib/ocaml/Belt_SortArray.cmti",
-    "lib/ocaml/Belt_SortArray.res",
-    "lib/ocaml/Belt_SortArray.resi",
-    "lib/ocaml/Belt_SortArrayInt.cmi",
-    "lib/ocaml/Belt_SortArrayInt.cmj",
-    "lib/ocaml/Belt_SortArrayInt.cmt",
-    "lib/ocaml/Belt_SortArrayInt.cmti",
-    "lib/ocaml/Belt_SortArrayInt.res",
-    "lib/ocaml/Belt_SortArrayInt.resi",
-    "lib/ocaml/Belt_SortArrayString.cmi",
-    "lib/ocaml/Belt_SortArrayString.cmj",
-    "lib/ocaml/Belt_SortArrayString.cmt",
-    "lib/ocaml/Belt_SortArrayString.cmti",
-    "lib/ocaml/Belt_SortArrayString.res",
-    "lib/ocaml/Belt_SortArrayString.resi",
-    "lib/ocaml/Belt_internalAVLset.cmi",
-    "lib/ocaml/Belt_internalAVLset.cmj",
-    "lib/ocaml/Belt_internalAVLset.cmt",
-    "lib/ocaml/Belt_internalAVLset.cmti",
-    "lib/ocaml/Belt_internalAVLset.res",
-    "lib/ocaml/Belt_internalAVLset.resi",
-    "lib/ocaml/Belt_internalAVLtree.cmi",
-    "lib/ocaml/Belt_internalAVLtree.cmj",
-    "lib/ocaml/Belt_internalAVLtree.cmt",
-    "lib/ocaml/Belt_internalAVLtree.cmti",
-    "lib/ocaml/Belt_internalAVLtree.res",
-    "lib/ocaml/Belt_internalAVLtree.resi",
-    "lib/ocaml/Belt_internalBuckets.cmi",
-    "lib/ocaml/Belt_internalBuckets.cmj",
-    "lib/ocaml/Belt_internalBuckets.cmt",
-    "lib/ocaml/Belt_internalBuckets.cmti",
-    "lib/ocaml/Belt_internalBuckets.res",
-    "lib/ocaml/Belt_internalBuckets.resi",
-    "lib/ocaml/Belt_internalBucketsType.cmi",
-    "lib/ocaml/Belt_internalBucketsType.cmj",
-    "lib/ocaml/Belt_internalBucketsType.cmt",
-    "lib/ocaml/Belt_internalBucketsType.cmti",
-    "lib/ocaml/Belt_internalBucketsType.res",
-    "lib/ocaml/Belt_internalBucketsType.resi",
-    "lib/ocaml/Belt_internalMapInt.cmi",
-    "lib/ocaml/Belt_internalMapInt.cmj",
-    "lib/ocaml/Belt_internalMapInt.cmt",
-    "lib/ocaml/Belt_internalMapInt.res",
-    "lib/ocaml/Belt_internalMapString.cmi",
-    "lib/ocaml/Belt_internalMapString.cmj",
-    "lib/ocaml/Belt_internalMapString.cmt",
-    "lib/ocaml/Belt_internalMapString.res",
-    "lib/ocaml/Belt_internalSetBuckets.cmi",
-    "lib/ocaml/Belt_internalSetBuckets.cmj",
-    "lib/ocaml/Belt_internalSetBuckets.cmt",
-    "lib/ocaml/Belt_internalSetBuckets.cmti",
-    "lib/ocaml/Belt_internalSetBuckets.res",
-    "lib/ocaml/Belt_internalSetBuckets.resi",
-    "lib/ocaml/Belt_internalSetInt.cmi",
-    "lib/ocaml/Belt_internalSetInt.cmj",
-    "lib/ocaml/Belt_internalSetInt.cmt",
-    "lib/ocaml/Belt_internalSetInt.res",
-    "lib/ocaml/Belt_internalSetString.cmi",
-    "lib/ocaml/Belt_internalSetString.cmj",
-    "lib/ocaml/Belt_internalSetString.cmt",
-    "lib/ocaml/Belt_internalSetString.res",
     "lib/ocaml/Char.cmi",
     "lib/ocaml/Char.cmj",
     "lib/ocaml/Char.cmt",
@@ -670,6 +338,12 @@
     "lib/ocaml/Primitive_js_extern.cmj",
     "lib/ocaml/Primitive_js_extern.cmt",
     "lib/ocaml/Primitive_js_extern.res",
+    "lib/ocaml/Primitive_list.cmi",
+    "lib/ocaml/Primitive_list.cmj",
+    "lib/ocaml/Primitive_list.cmt",
+    "lib/ocaml/Primitive_list.cmti",
+    "lib/ocaml/Primitive_list.res",
+    "lib/ocaml/Primitive_list.resi",
     "lib/ocaml/Primitive_module.cmi",
     "lib/ocaml/Primitive_module.cmj",
     "lib/ocaml/Primitive_module.cmt",
@@ -1093,5 +767,91 @@
     "lib/ocaml/Stdlib_WeakSet.cmt",
     "lib/ocaml/Stdlib_WeakSet.res",
     "package.json"
+  ],
+  "@rescript/belt": [
+    "README.md",
+    "package.json",
+    "rescript.json",
+    "src/Belt.res",
+    "src/Belt_Array.res",
+    "src/Belt_Array.resi",
+    "src/Belt_Float.res",
+    "src/Belt_Float.resi",
+    "src/Belt_HashMap.res",
+    "src/Belt_HashMap.resi",
+    "src/Belt_HashMapInt.res",
+    "src/Belt_HashMapInt.resi",
+    "src/Belt_HashMapString.res",
+    "src/Belt_HashMapString.resi",
+    "src/Belt_HashSet.res",
+    "src/Belt_HashSet.resi",
+    "src/Belt_HashSetInt.res",
+    "src/Belt_HashSetInt.resi",
+    "src/Belt_HashSetString.res",
+    "src/Belt_HashSetString.resi",
+    "src/Belt_Id.res",
+    "src/Belt_Id.resi",
+    "src/Belt_Int.res",
+    "src/Belt_Int.resi",
+    "src/Belt_List.res",
+    "src/Belt_List.resi",
+    "src/Belt_Map.res",
+    "src/Belt_Map.resi",
+    "src/Belt_MapDict.res",
+    "src/Belt_MapDict.resi",
+    "src/Belt_MapInt.res",
+    "src/Belt_MapInt.resi",
+    "src/Belt_MapString.res",
+    "src/Belt_MapString.resi",
+    "src/Belt_MutableMap.res",
+    "src/Belt_MutableMap.resi",
+    "src/Belt_MutableMapInt.res",
+    "src/Belt_MutableMapInt.resi",
+    "src/Belt_MutableMapString.res",
+    "src/Belt_MutableMapString.resi",
+    "src/Belt_MutableQueue.res",
+    "src/Belt_MutableQueue.resi",
+    "src/Belt_MutableSet.res",
+    "src/Belt_MutableSet.resi",
+    "src/Belt_MutableSetInt.res",
+    "src/Belt_MutableSetInt.resi",
+    "src/Belt_MutableSetString.res",
+    "src/Belt_MutableSetString.resi",
+    "src/Belt_MutableStack.res",
+    "src/Belt_MutableStack.resi",
+    "src/Belt_Option.res",
+    "src/Belt_Option.resi",
+    "src/Belt_Range.res",
+    "src/Belt_Range.resi",
+    "src/Belt_Result.res",
+    "src/Belt_Result.resi",
+    "src/Belt_Set.res",
+    "src/Belt_Set.resi",
+    "src/Belt_SetDict.res",
+    "src/Belt_SetDict.resi",
+    "src/Belt_SetInt.res",
+    "src/Belt_SetInt.resi",
+    "src/Belt_SetString.res",
+    "src/Belt_SetString.resi",
+    "src/Belt_SortArray.res",
+    "src/Belt_SortArray.resi",
+    "src/Belt_SortArrayInt.res",
+    "src/Belt_SortArrayInt.resi",
+    "src/Belt_SortArrayString.res",
+    "src/Belt_SortArrayString.resi",
+    "src/Belt_internalAVLset.res",
+    "src/Belt_internalAVLset.resi",
+    "src/Belt_internalAVLtree.res",
+    "src/Belt_internalAVLtree.resi",
+    "src/Belt_internalBuckets.res",
+    "src/Belt_internalBuckets.resi",
+    "src/Belt_internalBucketsType.res",
+    "src/Belt_internalBucketsType.resi",
+    "src/Belt_internalMapInt.res",
+    "src/Belt_internalMapString.res",
+    "src/Belt_internalSetBuckets.res",
+    "src/Belt_internalSetBuckets.resi",
+    "src/Belt_internalSetInt.res",
+    "src/Belt_internalSetString.res"
   ]
 }
\ No newline at end of file
diff --git a/packages/dev-playground/src/CompilerApi.res b/packages/dev-playground/src/CompilerApi.res
index 8503744155c..901eb314738 100644
--- a/packages/dev-playground/src/CompilerApi.res
+++ b/packages/dev-playground/src/CompilerApi.res
@@ -377,13 +377,24 @@ let loadRuntimeLibraries = async version => {
 
     let libraries = try {
       let _ = await loadScript(
-        versionAssetUrl(selectedVersion, "@rescript/react/cmij.js"),
+        versionAssetUrl(selectedVersion, "@rescript/belt/cmij.js"),
         ~cache=false,
       )
-      ["compiler-builtins", "@rescript/react"]
+      ["compiler-builtins", "@rescript/belt"]
     } catch {
     | _ => ["compiler-builtins"]
     }
+
+    let libraries = try {
+      let _ = await loadScript(
+        versionAssetUrl(selectedVersion, "@rescript/react/cmij.js"),
+        ~cache=false,
+      )
+      libraries->Array.concat(["@rescript/react"])
+    } catch {
+    | _ => libraries
+    }
+
     loadedLibrariesByVersion->Map.set(selectedVersion, libraries)
     activeLibraryVersion := Some(selectedVersion)
   }
diff --git a/packages/playground/README.md b/packages/playground/README.md
index bd8a8d706f7..1ef71110a76 100644
--- a/packages/playground/README.md
+++ b/packages/playground/README.md
@@ -20,6 +20,8 @@ All the cmij files will now be available in the `packages/` directory with a str
 tree packages
 packages
 └── @rescript
+    ├── belt
+    │   └── cmij.js
     └── react
         ├── React.js
         ├── ReactDOM.js
@@ -33,7 +35,7 @@ packages
         ├── RescriptReactRouter.js
         └── cmij.js
 
-2 directories, 11 files
+3 directories, 12 files
 ```
 
 ## Using cmij artifacts with the playground bundle
@@ -44,10 +46,11 @@ Let's assume our `compiler.js` file represents our playground bundle, you'd firs
 const { rescript_compiler } = require("./compiler.js");
 
 require("./packages/compiler-builtins/cmij.js");
+require("./packages/@rescript/belt/cmij.js");
 require("./packages/@rescript/react/cmij.js");
 
 let comp = rescript_compiler.make();
 comp.rescript.compile("let a = <div/>");
 ```
 
-The script above will be able to successfully compile this React code, since all the `React` module functionality required by JSX was injected in the compiler's state.
+The script above will be able to successfully compile code using Belt and React, since both libraries were injected into the compiler's state.
diff --git a/packages/playground/package.json b/packages/playground/package.json
index e9dde14c04b..13785056dd2 100644
--- a/packages/playground/package.json
+++ b/packages/playground/package.json
@@ -10,6 +10,7 @@
     "serve-bundle": "node serve-bundle.mjs"
   },
   "dependencies": {
+    "@rescript/belt": "workspace:^",
     "@rescript/react": "workspace:^",
     "rescript": "workspace:^"
   },
diff --git a/packages/playground/playground_test.cjs b/packages/playground/playground_test.cjs
index 051cb9efd6f..0aa38bea263 100644
--- a/packages/playground/playground_test.cjs
+++ b/packages/playground/playground_test.cjs
@@ -3,6 +3,7 @@
 const { rescript_compiler } = require("./compiler.js");
 
 require("./packages/compiler-builtins/cmij.js");
+require("./packages/@rescript/belt/cmij.js");
 require("./packages/@rescript/react/cmij.js");
 
 const compiler = rescript_compiler.make();
@@ -36,7 +37,7 @@ const result = compiler.rescript.compile(`
   }
 
   let sum = [1,2,3]
-    ->Array.map(x => x * 2)
+    ->Belt.Array.map(x => x * 2)
     ->Array.reduce(0, (acc, item) => acc + item)
 
 
diff --git a/packages/playground/rescript.json b/packages/playground/rescript.json
index a7349bd4123..ffdec5eba64 100644
--- a/packages/playground/rescript.json
+++ b/packages/playground/rescript.json
@@ -10,6 +10,7 @@
     "suffix": ".res.js"
   },
   "dependencies": [
+    "@rescript/belt",
     "@rescript/react"
   ]
 }
diff --git a/rewatch/testrepo/package.json b/rewatch/testrepo/package.json
index ad9299b611b..eacc5caf264 100644
--- a/rewatch/testrepo/package.json
+++ b/rewatch/testrepo/package.json
@@ -24,6 +24,8 @@
     ]
   },
   "dependencies": {
+    "@rescript/belt": "portal:../../packages/@rescript/belt",
+    "@rescript/runtime": "portal:../../packages/@rescript/runtime",
     "rescript": "12.0.0"
   },
   "scripts": {
diff --git a/rewatch/testrepo/packages/dep02/rescript.json b/rewatch/testrepo/packages/dep02/rescript.json
index f84064c9cf7..702d3483623 100644
--- a/rewatch/testrepo/packages/dep02/rescript.json
+++ b/rewatch/testrepo/packages/dep02/rescript.json
@@ -9,5 +9,5 @@
     "in-source": true
   },
   "suffix": ".bs.js",
-  "dependencies": ["@testrepo/new-namespace"]
+  "dependencies": ["@rescript/belt", "@testrepo/new-namespace"]
 }
diff --git a/rewatch/testrepo/packages/dep02/src/Array.mjs b/rewatch/testrepo/packages/dep02/src/Array.mjs
index edd4b1aa680..1d3a8c7bd31 100644
--- a/rewatch/testrepo/packages/dep02/src/Array.mjs
+++ b/rewatch/testrepo/packages/dep02/src/Array.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
-import * as Belt_SortArray from "@rescript/runtime/lib/es6/Belt_SortArray.mjs";
+import * as Belt_Array from "@rescript/belt/src/Belt_Array.mjs";
+import * as Belt_SortArray from "@rescript/belt/src/Belt_SortArray.mjs";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function includes(prim0, prim1) {
diff --git a/rewatch/testrepo/packages/main/rescript.json b/rewatch/testrepo/packages/main/rescript.json
index b26faec2af6..e4510889c94 100644
--- a/rewatch/testrepo/packages/main/rescript.json
+++ b/rewatch/testrepo/packages/main/rescript.json
@@ -9,5 +9,5 @@
     "in-source": true
   },
   "suffix": ".bs.js",
-  "dependencies": ["@testrepo/dep01"]
+  "dependencies": ["@rescript/belt", "@testrepo/dep01"]
 }
diff --git a/rewatch/testrepo/yarn.lock b/rewatch/testrepo/yarn.lock
index acd7382b24b..dc0bbcac2c6 100644
--- a/rewatch/testrepo/yarn.lock
+++ b/rewatch/testrepo/yarn.lock
@@ -5,6 +5,15 @@ __metadata:
   version: 8
   cacheKey: 10c0
 
+"@rescript/belt@portal:../../packages/@rescript/belt::locator=testrepo%40workspace%3A.":
+  version: 0.0.0-use.local
+  resolution: "@rescript/belt@portal:../../packages/@rescript/belt::locator=testrepo%40workspace%3A."
+  peerDependencies:
+    "@rescript/runtime": "workspace:^"
+    rescript: "workspace:^"
+  languageName: node
+  linkType: soft
+
 "@rescript/darwin-arm64@npm:12.0.0":
   version: 12.0.0
   resolution: "@rescript/darwin-arm64@npm:12.0.0"
@@ -75,6 +84,12 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@rescript/runtime@portal:../../packages/@rescript/runtime::locator=testrepo%40workspace%3A.":
+  version: 0.0.0-use.local
+  resolution: "@rescript/runtime@portal:../../packages/@rescript/runtime::locator=testrepo%40workspace%3A."
+  languageName: node
+  linkType: soft
+
 "@rescript/webapi@npm:0.1.0-experimental-73e6a0d":
   version: 0.1.0-experimental-73e6a0d
   resolution: "@rescript/webapi@npm:0.1.0-experimental-73e6a0d"
@@ -319,6 +334,8 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "testrepo@workspace:."
   dependencies:
+    "@rescript/belt": "portal:../../packages/@rescript/belt"
+    "@rescript/runtime": "portal:../../packages/@rescript/runtime"
     rescript: "npm:12.0.0"
   languageName: unknown
   linkType: soft
diff --git a/rewatch/tests/add-belt-dependencies.mjs b/rewatch/tests/add-belt-dependencies.mjs
new file mode 100644
index 00000000000..a50502a34ab
--- /dev/null
+++ b/rewatch/tests/add-belt-dependencies.mjs
@@ -0,0 +1,26 @@
+#!/usr/bin/env node
+
+import * as fs from "node:fs/promises";
+import * as path from "node:path";
+
+const testrepo = path.join(import.meta.dirname, "..", "testrepo");
+const configs = [
+  path.join(testrepo, "node_modules", "rescript-nodejs", "rescript.json"),
+  path.join(
+    testrepo,
+    "packages",
+    "nohoist",
+    "node_modules",
+    "rescript-bun",
+    "rescript.json",
+  ),
+];
+
+for (const configPath of configs) {
+  const config = JSON.parse(await fs.readFile(configPath, "utf8"));
+  const dependencies = config.dependencies ?? [];
+  if (!dependencies.includes("@rescript/belt")) {
+    config.dependencies = ["@rescript/belt", ...dependencies];
+    await fs.writeFile(configPath, `${JSON.stringify(config, null, 2)}\n`);
+  }
+}
diff --git a/rewatch/tests/snapshots/clean-rebuild.txt b/rewatch/tests/snapshots/clean-rebuild.txt
index 078429af4f3..7f2b25aceb7 100644
--- a/rewatch/tests/snapshots/clean-rebuild.txt
+++ b/rewatch/tests/snapshots/clean-rebuild.txt
@@ -1,6 +1,6 @@
 Cleaned 0/0
-Parsed 429 source files
-Compiled 429 modules
+Parsed 472 source files
+Compiled 472 modules
 
   Warning number 32
   /packages/watch-warnings/src/ModuleA.res:1:5-15
diff --git a/rewatch/tests/snapshots/dependency-cycle.txt b/rewatch/tests/snapshots/dependency-cycle.txt
index de1c236b403..06f73f80deb 100644
--- a/rewatch/tests/snapshots/dependency-cycle.txt
+++ b/rewatch/tests/snapshots/dependency-cycle.txt
@@ -1,4 +1,4 @@
-Cleaned 0/429
+Cleaned 0/510
 Parsed 2 source files
 Compiled 1 modules
 
diff --git a/rewatch/tests/snapshots/dev-dependency-used-by-non-dev-source.txt b/rewatch/tests/snapshots/dev-dependency-used-by-non-dev-source.txt
index 142123ab1b9..578189b4b2a 100644
--- a/rewatch/tests/snapshots/dev-dependency-used-by-non-dev-source.txt
+++ b/rewatch/tests/snapshots/dev-dependency-used-by-non-dev-source.txt
@@ -1,4 +1,4 @@
-Cleaned 0/429
+Cleaned 0/510
 Parsed 2 source files
 Compiled 2 modules
 
diff --git a/rewatch/tests/snapshots/remove-file.txt b/rewatch/tests/snapshots/remove-file.txt
index 4c622363304..78756a9b83f 100644
--- a/rewatch/tests/snapshots/remove-file.txt
+++ b/rewatch/tests/snapshots/remove-file.txt
@@ -1,4 +1,4 @@
-Cleaned 1/429
+Cleaned 1/510
 Parsed 1 source files
 Compiled 2 modules
 
diff --git a/rewatch/tests/snapshots/rename-file-internal-dep-namespace.txt b/rewatch/tests/snapshots/rename-file-internal-dep-namespace.txt
index e3f50855e36..bcd4157e4ef 100644
--- a/rewatch/tests/snapshots/rename-file-internal-dep-namespace.txt
+++ b/rewatch/tests/snapshots/rename-file-internal-dep-namespace.txt
@@ -1,4 +1,4 @@
-Cleaned 1/429
+Cleaned 1/510
 Parsed 2 source files
 Compiled 3 modules
 
diff --git a/rewatch/tests/snapshots/rename-file-internal-dep.txt b/rewatch/tests/snapshots/rename-file-internal-dep.txt
index da66be5aafa..39989f4bba5 100644
--- a/rewatch/tests/snapshots/rename-file-internal-dep.txt
+++ b/rewatch/tests/snapshots/rename-file-internal-dep.txt
@@ -1,4 +1,4 @@
-Cleaned 1/429
+Cleaned 1/510
 Parsed 2 source files
 Compiled 3 modules
 
diff --git a/rewatch/tests/snapshots/rename-file-with-interface.txt b/rewatch/tests/snapshots/rename-file-with-interface.txt
index 18f72c6c17a..f33ff54867b 100644
--- a/rewatch/tests/snapshots/rename-file-with-interface.txt
+++ b/rewatch/tests/snapshots/rename-file-with-interface.txt
@@ -1,5 +1,5 @@
 
 No implementation file found for interface file (skipping): src/ModuleWithInterface.resi
-Cleaned 2/429
+Cleaned 2/510
 Parsed 2 source files
 Compiled 2 modules
 
diff --git a/rewatch/tests/snapshots/rename-file.txt b/rewatch/tests/snapshots/rename-file.txt
index 24664e6638b..c63fe8b997e 100644
--- a/rewatch/tests/snapshots/rename-file.txt
+++ b/rewatch/tests/snapshots/rename-file.txt
@@ -1,4 +1,4 @@
-Cleaned 1/429
+Cleaned 1/510
 Parsed 2 source files
 Compiled 2 modules
 
diff --git a/rewatch/tests/snapshots/rename-interface-file.txt b/rewatch/tests/snapshots/rename-interface-file.txt
index d818b4f72f5..1b27f5bbfb6 100644
--- a/rewatch/tests/snapshots/rename-interface-file.txt
+++ b/rewatch/tests/snapshots/rename-interface-file.txt
@@ -1,5 +1,5 @@
 
 No implementation file found for interface file (skipping): src/ModuleWithInterface2.resi
-Cleaned 1/429
+Cleaned 1/510
 Parsed 2 source files
 Compiled 2 modules
 
diff --git a/rewatch/tests/suite.sh b/rewatch/tests/suite.sh
index 2d73503c878..22cc77935d7 100755
--- a/rewatch/tests/suite.sh
+++ b/rewatch/tests/suite.sh
@@ -41,6 +41,7 @@ success "No stale rescript processes found"
 # the repository-built compiler and runtime. See ../testrepo/README.md.
 bold "Yarn install"
 (cd ../testrepo && yarn)
+node ./add-belt-dependencies.mjs
 
 bold "Rescript version"
 (cd ../testrepo && ./node_modules/.bin/rescript --version)
diff --git a/scripts/res/GenApiDocs.res b/scripts/res/GenApiDocs.res
index 49d8323a91e..bf72d64cdf6 100644
--- a/scripts/res/GenApiDocs.res
+++ b/scripts/res/GenApiDocs.res
@@ -23,7 +23,11 @@ if !Fs.existsSync(dirVersion) {
 }
 
 
-let entryPointFiles = ["Belt.res", "Dom.res", "Stdlib.res"]
+let entryPointFiles = [
+  ("belt", "Belt.res"),
+  ("runtime", "Dom.res"),
+  ("runtime", "Stdlib.res"),
+]
 
 let hiddenModules = []
 
@@ -44,9 +48,17 @@ type section = {
 
 let env = Process.env
 
-let docsDecoded = entryPointFiles->Array.map(libFile =>
+let docsDecoded = entryPointFiles->Array.map(((packageName, libFile)) =>
   try {
-    let entryPointFile = Path.join([Node.dirname, "..", "..", "packages", "@rescript", "runtime", libFile])
+    let entryPointFile = Path.join([
+      Node.dirname,
+      "..",
+      "..",
+      "packages",
+      "@rescript",
+      packageName,
+      packageName == "runtime" ? libFile : Path.join(["src", libFile]),
+    ])
 
     let rescriptToolsPath = Path.join([Node.dirname, "..", "..", "cli", "rescript-tools.js"])
     let output = ChildProcess.execSync(
diff --git a/scripts/test.js b/scripts/test.js
index 1c9bf3fe752..a59676a0e48 100644
--- a/scripts/test.js
+++ b/scripts/test.js
@@ -73,18 +73,36 @@ if (ounitTest) {
 }
 
 if (mochaTest) {
+  const beltPackageDir = path.join(projectDir, "packages/@rescript/belt");
+  const beltTestDir = path.join(projectDir, "tests/belt_tests");
+
   // No need to clean beforehand, rewatch detects changes to the compiler binary
   // and rebuilds automatically in that case.
   await execBuild([], {
     cwd: compilerTestDir,
     stdio: "inherit",
   });
+  // The CommonJS tests clean their dependencies, including Belt. Force a full
+  // rebuild so repeated test runs don't rely on stale dependency artifacts.
+  await execClean([], {
+    cwd: beltPackageDir,
+    stdio: "inherit",
+  });
+  await execBuild([], {
+    cwd: beltPackageDir,
+    stdio: "inherit",
+  });
+  await execBuild([], {
+    cwd: beltTestDir,
+    stdio: "inherit",
+  });
 
   await mocha(
     [
       "-t",
       "10000",
       "tests/tests/src/**/*_test.mjs",
+      "tests/belt_tests/src/**/*_test.mjs",
       // Ignore the preserve_jsx_test.mjs file.
       // I can't run because Mocha doesn't support jsx.
       // We also want to keep the output as is.
@@ -109,6 +127,10 @@ if (mochaTest) {
 
   // CommonJS tests
   const commonjsTestDir = path.join(projectDir, "tests/commonjs_tests");
+  await execClean([], {
+    cwd: commonjsTestDir,
+    stdio: "inherit",
+  });
   await execBuild([], {
     cwd: commonjsTestDir,
     stdio: "inherit",
diff --git a/scripts/updateArtifactList.js b/scripts/updateArtifactList.js
index 8d5ad1b7e6e..11dbfb10ced 100755
--- a/scripts/updateArtifactList.js
+++ b/scripts/updateArtifactList.js
@@ -55,7 +55,7 @@ async function getArtifacts(pkg) {
 /** @type {Record<string, string[]>} */
 const artifactsPerPackage = {};
 
-for (const pkg of ["rescript", "@rescript/runtime"]) {
+for (const pkg of ["rescript", "@rescript/runtime", "@rescript/belt"]) {
   artifactsPerPackage[pkg] = await getArtifacts(pkg);
 }
 
diff --git a/tests/analysis_tests/Makefile b/tests/analysis_tests/Makefile
index 741c90403ec..b14ee5cd5ae 100644
--- a/tests/analysis_tests/Makefile
+++ b/tests/analysis_tests/Makefile
@@ -7,7 +7,12 @@ test-analysis-binary:
 	make -C tests-namespaced-references test
 	make -C tests-sourcedirs-dependency test
 
+# Belt is shared by CommonJS and ES module test projects. Rebuild it until
+# Rewatch invalidates source dependencies when package output settings change:
+# https://github.com/rescript-lang/rescript/issues/8539
 test-reanalyze:
+	yarn workspace @rescript/belt rescript clean
+	yarn workspace @rescript/belt build
 	make -C tests-reanalyze test
 
 test: test-analysis-binary test-reanalyze
diff --git a/tests/analysis_tests/tests-reanalyze/deadcode/package.json b/tests/analysis_tests/tests-reanalyze/deadcode/package.json
index bff46bce04f..b40d999bc70 100644
--- a/tests/analysis_tests/tests-reanalyze/deadcode/package.json
+++ b/tests/analysis_tests/tests-reanalyze/deadcode/package.json
@@ -6,6 +6,7 @@
     "clean": "rescript clean"
   },
   "dependencies": {
+    "@rescript/belt": "workspace:^",
     "@rescript/react": "workspace:^",
     "rescript": "workspace:^"
   }
diff --git a/tests/analysis_tests/tests-reanalyze/deadcode/rescript.json b/tests/analysis_tests/tests-reanalyze/deadcode/rescript.json
index 30af93d1ce8..58d3c4d4148 100644
--- a/tests/analysis_tests/tests-reanalyze/deadcode/rescript.json
+++ b/tests/analysis_tests/tests-reanalyze/deadcode/rescript.json
@@ -7,7 +7,7 @@
   },
   "name": "@tests/reanalyze-deadcode",
   "jsx": { "version": 4 },
-  "dependencies": ["@rescript/react"],
+  "dependencies": ["@rescript/belt", "@rescript/react"],
   "sources": [
     {
       "dir": "src",
diff --git a/tests/analysis_tests/tests/not_compiled/SemanticTokensList.res b/tests/analysis_tests/tests/not_compiled/SemanticTokensList.res
new file mode 100644
index 00000000000..c435310fe4d
--- /dev/null
+++ b/tests/analysis_tests/tests/not_compiled/SemanticTokensList.res
@@ -0,0 +1,3 @@
+let xs = list{1, 2}
+let ys = list{...xs, 3}
+//^sem
diff --git a/tests/analysis_tests/tests/not_compiled/expected/SemanticTokensList.res.txt b/tests/analysis_tests/tests/not_compiled/expected/SemanticTokensList.res.txt
new file mode 100644
index 00000000000..56bd7778271
--- /dev/null
+++ b/tests/analysis_tests/tests/not_compiled/expected/SemanticTokensList.res.txt
@@ -0,0 +1,2 @@
+{ "data": [ 0, 4, 2, 1, 0, 1, 4, 2, 1, 0, 0, 13, 2, 1, 0 ] }
+
diff --git a/tests/analysis_tests/tests/package.json b/tests/analysis_tests/tests/package.json
index cabac4a3ebc..5e367b05fee 100644
--- a/tests/analysis_tests/tests/package.json
+++ b/tests/analysis_tests/tests/package.json
@@ -6,6 +6,7 @@
     "clean": "rescript clean"
   },
   "dependencies": {
+    "@rescript/belt": "workspace:^",
     "@rescript/react": "workspace:^",
     "rescript": "workspace:^"
   }
diff --git a/tests/analysis_tests/tests/rescript.json b/tests/analysis_tests/tests/rescript.json
index f87f7d538a2..2e73a069187 100644
--- a/tests/analysis_tests/tests/rescript.json
+++ b/tests/analysis_tests/tests/rescript.json
@@ -10,7 +10,7 @@
     }
   ],
   "compiler-flags": ["-w -33-44-8-26-27-110"],
-  "dependencies": ["@rescript/react"],
+  "dependencies": ["@rescript/belt", "@rescript/react"],
   "jsx": { "version": 4 },
   "package-specs": [{ "module": "commonjs", "in-source": false }],
   "suffix": ".res.js",
diff --git a/tests/analysis_tests/tests/src/expected/CompletionAttributes.res.txt b/tests/analysis_tests/tests/src/expected/CompletionAttributes.res.txt
index ee833853eec..926cde0dcc2 100644
--- a/tests/analysis_tests/tests/src/expected/CompletionAttributes.res.txt
+++ b/tests/analysis_tests/tests/src/expected/CompletionAttributes.res.txt
@@ -24,6 +24,7 @@ Completable: CdecoratorPayload(module=)
 Package opens Stdlib.place holder Pervasives.JsxModules.place holder
 Resolved opens 1 Stdlib
 [
+  { "detail": "Package", "kind": 4, "label": "@rescript/belt", "tags": [] },
   { "detail": "Package", "kind": 4, "label": "@rescript/react", "tags": [] },
   { "detail": "Local file", "kind": 4, "label": "./test.json", "tags": [] },
   { "detail": "Local file", "kind": 4, "label": "./tst.js", "tags": [] }
@@ -233,6 +234,7 @@ Completable: CdecoratorPayload(module=)
 Package opens Stdlib.place holder Pervasives.JsxModules.place holder
 Resolved opens 1 Stdlib
 [
+  { "detail": "Package", "kind": 4, "label": "@rescript/belt", "tags": [] },
   { "detail": "Package", "kind": 4, "label": "@rescript/react", "tags": [] },
   { "detail": "Local file", "kind": 4, "label": "./test.json", "tags": [] },
   { "detail": "Local file", "kind": 4, "label": "./tst.js", "tags": [] }
@@ -244,6 +246,7 @@ Completable: CdecoratorPayload(module=)
 Package opens Stdlib.place holder Pervasives.JsxModules.place holder
 Resolved opens 1 Stdlib
 [
+  { "detail": "Package", "kind": 4, "label": "@rescript/belt", "tags": [] },
   { "detail": "Package", "kind": 4, "label": "@rescript/react", "tags": [] },
   { "detail": "Local file", "kind": 4, "label": "./test.json", "tags": [] },
   { "detail": "Local file", "kind": 4, "label": "./tst.js", "tags": [] }
diff --git a/tests/belt_tests/package.json b/tests/belt_tests/package.json
new file mode 100644
index 00000000000..1e452242fb3
--- /dev/null
+++ b/tests/belt_tests/package.json
@@ -0,0 +1,10 @@
+{
+  "name": "@tests/belt",
+  "private": true,
+  "type": "module",
+  "dependencies": {
+    "@rescript/belt": "workspace:^",
+    "mocha": "11.7.6",
+    "rescript": "workspace:^"
+  }
+}
diff --git a/tests/belt_tests/rescript.json b/tests/belt_tests/rescript.json
new file mode 100644
index 00000000000..dadb4350db4
--- /dev/null
+++ b/tests/belt_tests/rescript.json
@@ -0,0 +1,18 @@
+{
+  "name": "@tests/belt",
+  "sources": [
+    {
+      "dir": "src"
+    }
+  ],
+  "package-specs": {
+    "module": "esmodule",
+    "in-source": true,
+    "suffix": ".mjs"
+  },
+  "dependencies": ["@rescript/belt"],
+  "compiler-flags": [
+    "-w -3-6-26-27-29-30-32..40-44-45-52-60-9-106+104",
+    "-warn-error A"
+  ]
+}
diff --git a/tests/tests/src/array_data_util.mjs b/tests/belt_tests/src/array_data_util.mjs
similarity index 82%
rename from tests/tests/src/array_data_util.mjs
rename to tests/belt_tests/src/array_data_util.mjs
index 2e43750e14e..1140f312706 100644
--- a/tests/tests/src/array_data_util.mjs
+++ b/tests/belt_tests/src/array_data_util.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 
 function range(i, j) {
   return Belt_Array.makeBy((j - i | 0) + 1 | 0, k => k + i | 0);
diff --git a/tests/tests/src/array_data_util.res b/tests/belt_tests/src/array_data_util.res
similarity index 100%
rename from tests/tests/src/array_data_util.res
rename to tests/belt_tests/src/array_data_util.res
diff --git a/tests/tests/src/belt_float_test.mjs b/tests/belt_tests/src/belt_float_test.mjs
similarity index 97%
rename from tests/tests/src/belt_float_test.mjs
rename to tests/belt_tests/src/belt_float_test.mjs
index d424e7d5c16..8b684785693 100644
--- a/tests/tests/src/belt_float_test.mjs
+++ b/tests/belt_tests/src/belt_float_test.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Float from "@rescript/runtime/lib/es6/Belt_Float.mjs";
+import * as Belt_Float from "@rescript/belt/lib/es6/src/Belt_Float.mjs";
 import * as Test_utils from "./test_utils.mjs";
 
 Mocha.describe("Belt_float_test", () => {
diff --git a/tests/tests/src/belt_float_test.res b/tests/belt_tests/src/belt_float_test.res
similarity index 100%
rename from tests/tests/src/belt_float_test.res
rename to tests/belt_tests/src/belt_float_test.res
diff --git a/tests/tests/src/belt_hashmap_test.mjs b/tests/belt_tests/src/belt_hashmap_test.mjs
similarity index 89%
rename from tests/tests/src/belt_hashmap_test.mjs
rename to tests/belt_tests/src/belt_hashmap_test.mjs
index 62d33a0b7e7..d38d5dd06a9 100644
--- a/tests/tests/src/belt_hashmap_test.mjs
+++ b/tests/belt_tests/src/belt_hashmap_test.mjs
@@ -1,13 +1,13 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Id from "@rescript/runtime/lib/es6/Belt_Id.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Id from "@rescript/belt/lib/es6/src/Belt_Id.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Hash_utils from "./hash_utils.mjs";
 import * as Test_utils from "./test_utils.mjs";
-import * as Belt_HashMap from "@rescript/runtime/lib/es6/Belt_HashMap.mjs";
+import * as Belt_HashMap from "@rescript/belt/lib/es6/src/Belt_HashMap.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
-import * as Belt_SortArray from "@rescript/runtime/lib/es6/Belt_SortArray.mjs";
+import * as Belt_SortArray from "@rescript/belt/lib/es6/src/Belt_SortArray.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
 
 function intEq(x, y) {
diff --git a/tests/tests/src/belt_hashmap_test.res b/tests/belt_tests/src/belt_hashmap_test.res
similarity index 100%
rename from tests/tests/src/belt_hashmap_test.res
rename to tests/belt_tests/src/belt_hashmap_test.res
diff --git a/tests/tests/src/belt_hashset_int_test.mjs b/tests/belt_tests/src/belt_hashset_int_test.mjs
similarity index 90%
rename from tests/tests/src/belt_hashset_int_test.mjs
rename to tests/belt_tests/src/belt_hashset_int_test.mjs
index d24f7bbae60..159f97cb719 100644
--- a/tests/tests/src/belt_hashset_int_test.mjs
+++ b/tests/belt_tests/src/belt_hashset_int_test.mjs
@@ -1,12 +1,12 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
-import * as Belt_SetInt from "@rescript/runtime/lib/es6/Belt_SetInt.mjs";
+import * as Belt_SetInt from "@rescript/belt/lib/es6/src/Belt_SetInt.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
-import * as Belt_HashSetInt from "@rescript/runtime/lib/es6/Belt_HashSetInt.mjs";
-import * as Belt_SortArrayInt from "@rescript/runtime/lib/es6/Belt_SortArrayInt.mjs";
+import * as Belt_HashSetInt from "@rescript/belt/lib/es6/src/Belt_HashSetInt.mjs";
+import * as Belt_SortArrayInt from "@rescript/belt/lib/es6/src/Belt_SortArrayInt.mjs";
 
 function add(x, y) {
   return x + y | 0;
diff --git a/tests/tests/src/belt_hashset_int_test.res b/tests/belt_tests/src/belt_hashset_int_test.res
similarity index 100%
rename from tests/tests/src/belt_hashset_int_test.res
rename to tests/belt_tests/src/belt_hashset_int_test.res
diff --git a/tests/tests/src/belt_int_test.mjs b/tests/belt_tests/src/belt_int_test.mjs
similarity index 97%
rename from tests/tests/src/belt_int_test.mjs
rename to tests/belt_tests/src/belt_int_test.mjs
index 6abc1bb12fe..10fdfbbcdd1 100644
--- a/tests/tests/src/belt_int_test.mjs
+++ b/tests/belt_tests/src/belt_int_test.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Int from "@rescript/runtime/lib/es6/Belt_Int.mjs";
+import * as Belt_Int from "@rescript/belt/lib/es6/src/Belt_Int.mjs";
 import * as Test_utils from "./test_utils.mjs";
 
 Mocha.describe("Belt_int_test", () => {
diff --git a/tests/tests/src/belt_int_test.res b/tests/belt_tests/src/belt_int_test.res
similarity index 100%
rename from tests/tests/src/belt_int_test.res
rename to tests/belt_tests/src/belt_int_test.res
diff --git a/tests/tests/src/belt_list_test.mjs b/tests/belt_tests/src/belt_list_test.mjs
similarity index 99%
rename from tests/tests/src/belt_list_test.mjs
rename to tests/belt_tests/src/belt_list_test.mjs
index 3eb0243519e..395ea5da21c 100644
--- a/tests/tests/src/belt_list_test.mjs
+++ b/tests/belt_tests/src/belt_list_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
diff --git a/tests/tests/src/belt_list_test.res b/tests/belt_tests/src/belt_list_test.res
similarity index 100%
rename from tests/tests/src/belt_list_test.res
rename to tests/belt_tests/src/belt_list_test.res
diff --git a/tests/tests/src/belt_mapint_test.mjs b/tests/belt_tests/src/belt_mapint_test.mjs
similarity index 90%
rename from tests/tests/src/belt_mapint_test.mjs
rename to tests/belt_tests/src/belt_mapint_test.mjs
index 9b7d1b9ccfc..11fde6a0c8a 100644
--- a/tests/tests/src/belt_mapint_test.mjs
+++ b/tests/belt_tests/src/belt_mapint_test.mjs
@@ -2,7 +2,7 @@
 
 import * as Mocha from "mocha";
 import * as Test_utils from "./test_utils.mjs";
-import * as Belt_MapInt from "@rescript/runtime/lib/es6/Belt_MapInt.mjs";
+import * as Belt_MapInt from "@rescript/belt/lib/es6/src/Belt_MapInt.mjs";
 
 Mocha.describe("Belt_mapint_test", () => {
   Mocha.test("set", () => {
diff --git a/tests/tests/src/belt_mapint_test.res b/tests/belt_tests/src/belt_mapint_test.res
similarity index 100%
rename from tests/tests/src/belt_mapint_test.res
rename to tests/belt_tests/src/belt_mapint_test.res
diff --git a/tests/tests/src/belt_result_alias_test.mjs b/tests/belt_tests/src/belt_result_alias_test.mjs
similarity index 77%
rename from tests/tests/src/belt_result_alias_test.mjs
rename to tests/belt_tests/src/belt_result_alias_test.mjs
index 4bf69e4f5fe..c843910b845 100644
--- a/tests/tests/src/belt_result_alias_test.mjs
+++ b/tests/belt_tests/src/belt_result_alias_test.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Result from "@rescript/runtime/lib/es6/Belt_Result.mjs";
+import * as Belt_Result from "@rescript/belt/lib/es6/src/Belt_Result.mjs";
 
 Belt_Result.map({
   TAG: "Ok",
diff --git a/tests/tests/src/belt_result_alias_test.res b/tests/belt_tests/src/belt_result_alias_test.res
similarity index 100%
rename from tests/tests/src/belt_result_alias_test.res
rename to tests/belt_tests/src/belt_result_alias_test.res
diff --git a/tests/tests/src/belt_sortarray_test.mjs b/tests/belt_tests/src/belt_sortarray_test.mjs
similarity index 96%
rename from tests/tests/src/belt_sortarray_test.mjs
rename to tests/belt_tests/src/belt_sortarray_test.mjs
index 57e73eb832a..c9d9cbb9d4b 100644
--- a/tests/tests/src/belt_sortarray_test.mjs
+++ b/tests/belt_tests/src/belt_sortarray_test.mjs
@@ -1,12 +1,12 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
-import * as Belt_Range from "@rescript/runtime/lib/es6/Belt_Range.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
+import * as Belt_Range from "@rescript/belt/lib/es6/src/Belt_Range.mjs";
 import * as Test_utils from "./test_utils.mjs";
-import * as Belt_SortArray from "@rescript/runtime/lib/es6/Belt_SortArray.mjs";
+import * as Belt_SortArray from "@rescript/belt/lib/es6/src/Belt_SortArray.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
-import * as Belt_SortArrayInt from "@rescript/runtime/lib/es6/Belt_SortArrayInt.mjs";
+import * as Belt_SortArrayInt from "@rescript/belt/lib/es6/src/Belt_SortArrayInt.mjs";
 
 function cmp(x, y) {
   return x - y | 0;
diff --git a/tests/tests/src/belt_sortarray_test.res b/tests/belt_tests/src/belt_sortarray_test.res
similarity index 100%
rename from tests/tests/src/belt_sortarray_test.res
rename to tests/belt_tests/src/belt_sortarray_test.res
diff --git a/tests/tests/src/bs_array_test.mjs b/tests/belt_tests/src/bs_array_test.mjs
similarity index 99%
rename from tests/tests/src/bs_array_test.mjs
rename to tests/belt_tests/src/bs_array_test.mjs
index b0cdf6d1c4d..74bd6912029 100644
--- a/tests/tests/src/bs_array_test.mjs
+++ b/tests/belt_tests/src/bs_array_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
diff --git a/tests/tests/src/bs_array_test.res b/tests/belt_tests/src/bs_array_test.res
similarity index 100%
rename from tests/tests/src/bs_array_test.res
rename to tests/belt_tests/src/bs_array_test.res
diff --git a/tests/tests/src/bs_map_set_dict_test.mjs b/tests/belt_tests/src/bs_map_set_dict_test.mjs
similarity index 86%
rename from tests/tests/src/bs_map_set_dict_test.mjs
rename to tests/belt_tests/src/bs_map_set_dict_test.mjs
index 1a34072de82..ced362803af 100644
--- a/tests/tests/src/bs_map_set_dict_test.mjs
+++ b/tests/belt_tests/src/bs_map_set_dict_test.mjs
@@ -1,14 +1,14 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Id from "@rescript/runtime/lib/es6/Belt_Id.mjs";
-import * as Belt_Map from "@rescript/runtime/lib/es6/Belt_Map.mjs";
-import * as Belt_Set from "@rescript/runtime/lib/es6/Belt_Set.mjs";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Id from "@rescript/belt/lib/es6/src/Belt_Id.mjs";
+import * as Belt_Map from "@rescript/belt/lib/es6/src/Belt_Map.mjs";
+import * as Belt_Set from "@rescript/belt/lib/es6/src/Belt_Set.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
-import * as Belt_MapDict from "@rescript/runtime/lib/es6/Belt_MapDict.mjs";
-import * as Belt_SetDict from "@rescript/runtime/lib/es6/Belt_SetDict.mjs";
+import * as Belt_MapDict from "@rescript/belt/lib/es6/src/Belt_MapDict.mjs";
+import * as Belt_SetDict from "@rescript/belt/lib/es6/src/Belt_SetDict.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
 
diff --git a/tests/tests/src/bs_map_set_dict_test.res b/tests/belt_tests/src/bs_map_set_dict_test.res
similarity index 100%
rename from tests/tests/src/bs_map_set_dict_test.res
rename to tests/belt_tests/src/bs_map_set_dict_test.res
diff --git a/tests/tests/src/bs_map_test.mjs b/tests/belt_tests/src/bs_map_test.mjs
similarity index 77%
rename from tests/tests/src/bs_map_test.mjs
rename to tests/belt_tests/src/bs_map_test.mjs
index 66a034bf8d4..9bad714f74a 100644
--- a/tests/tests/src/bs_map_test.mjs
+++ b/tests/belt_tests/src/bs_map_test.mjs
@@ -1,9 +1,9 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
-import * as Belt_MapInt from "@rescript/runtime/lib/es6/Belt_MapInt.mjs";
-import * as Belt_SetInt from "@rescript/runtime/lib/es6/Belt_SetInt.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
+import * as Belt_MapInt from "@rescript/belt/lib/es6/src/Belt_MapInt.mjs";
+import * as Belt_SetInt from "@rescript/belt/lib/es6/src/Belt_SetInt.mjs";
 
 let mapOfArray = Belt_MapInt.fromArray;
 
diff --git a/tests/tests/src/bs_map_test.res b/tests/belt_tests/src/bs_map_test.res
similarity index 100%
rename from tests/tests/src/bs_map_test.res
rename to tests/belt_tests/src/bs_map_test.res
diff --git a/tests/tests/src/bs_mutable_set_test.mjs b/tests/belt_tests/src/bs_mutable_set_test.mjs
similarity index 98%
rename from tests/tests/src/bs_mutable_set_test.mjs
rename to tests/belt_tests/src/bs_mutable_set_test.mjs
index 6b9f967a068..a57eaae9bb7 100644
--- a/tests/tests/src/bs_mutable_set_test.mjs
+++ b/tests/belt_tests/src/bs_mutable_set_test.mjs
@@ -1,12 +1,12 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
-import * as Belt_Range from "@rescript/runtime/lib/es6/Belt_Range.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
+import * as Belt_Range from "@rescript/belt/lib/es6/src/Belt_Range.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
-import * as Belt_MutableSetInt from "@rescript/runtime/lib/es6/Belt_MutableSetInt.mjs";
+import * as Belt_MutableSetInt from "@rescript/belt/lib/es6/src/Belt_MutableSetInt.mjs";
 
 Mocha.describe("Bs_mutable_set_test", () => {
   Mocha.test("mutable set basic operations", () => {
diff --git a/tests/tests/src/bs_mutable_set_test.res b/tests/belt_tests/src/bs_mutable_set_test.res
similarity index 100%
rename from tests/tests/src/bs_mutable_set_test.res
rename to tests/belt_tests/src/bs_mutable_set_test.res
diff --git a/tests/tests/src/bs_poly_map_test.mjs b/tests/belt_tests/src/bs_poly_map_test.mjs
similarity index 96%
rename from tests/tests/src/bs_poly_map_test.mjs
rename to tests/belt_tests/src/bs_poly_map_test.mjs
index 4a24f1e4c10..9da7230bb82 100644
--- a/tests/tests/src/bs_poly_map_test.mjs
+++ b/tests/belt_tests/src/bs_poly_map_test.mjs
@@ -1,10 +1,10 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Id from "@rescript/runtime/lib/es6/Belt_Id.mjs";
-import * as Belt_Map from "@rescript/runtime/lib/es6/Belt_Map.mjs";
-import * as Belt_Set from "@rescript/runtime/lib/es6/Belt_Set.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Id from "@rescript/belt/lib/es6/src/Belt_Id.mjs";
+import * as Belt_Map from "@rescript/belt/lib/es6/src/Belt_Map.mjs";
+import * as Belt_Set from "@rescript/belt/lib/es6/src/Belt_Set.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
diff --git a/tests/tests/src/bs_poly_map_test.res b/tests/belt_tests/src/bs_poly_map_test.res
similarity index 100%
rename from tests/tests/src/bs_poly_map_test.res
rename to tests/belt_tests/src/bs_poly_map_test.res
diff --git a/tests/tests/src/bs_poly_mutable_map_test.mjs b/tests/belt_tests/src/bs_poly_mutable_map_test.mjs
similarity index 87%
rename from tests/tests/src/bs_poly_mutable_map_test.mjs
rename to tests/belt_tests/src/bs_poly_mutable_map_test.mjs
index 67a795d0e91..bbc34855e3e 100644
--- a/tests/tests/src/bs_poly_mutable_map_test.mjs
+++ b/tests/belt_tests/src/bs_poly_mutable_map_test.mjs
@@ -1,13 +1,13 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Id from "@rescript/runtime/lib/es6/Belt_Id.mjs";
-import * as Belt_Set from "@rescript/runtime/lib/es6/Belt_Set.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Id from "@rescript/belt/lib/es6/src/Belt_Id.mjs";
+import * as Belt_Set from "@rescript/belt/lib/es6/src/Belt_Set.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
-import * as Belt_MutableMap from "@rescript/runtime/lib/es6/Belt_MutableMap.mjs";
+import * as Belt_MutableMap from "@rescript/belt/lib/es6/src/Belt_MutableMap.mjs";
 
 let Icmp = Belt_Id.comparable(Primitive_int.compare);
 
diff --git a/tests/tests/src/bs_poly_mutable_map_test.res b/tests/belt_tests/src/bs_poly_mutable_map_test.res
similarity index 100%
rename from tests/tests/src/bs_poly_mutable_map_test.res
rename to tests/belt_tests/src/bs_poly_mutable_map_test.res
diff --git a/tests/tests/src/bs_poly_mutable_set_test.mjs b/tests/belt_tests/src/bs_poly_mutable_set_test.mjs
similarity index 97%
rename from tests/tests/src/bs_poly_mutable_set_test.mjs
rename to tests/belt_tests/src/bs_poly_mutable_set_test.mjs
index 40c03e50675..f0acb9fcbc7 100644
--- a/tests/tests/src/bs_poly_mutable_set_test.mjs
+++ b/tests/belt_tests/src/bs_poly_mutable_set_test.mjs
@@ -1,13 +1,13 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Id from "@rescript/runtime/lib/es6/Belt_Id.mjs";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Id from "@rescript/belt/lib/es6/src/Belt_Id.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
-import * as Belt_MutableSet from "@rescript/runtime/lib/es6/Belt_MutableSet.mjs";
+import * as Belt_MutableSet from "@rescript/belt/lib/es6/src/Belt_MutableSet.mjs";
 
 let IntCmp = Belt_Id.comparable(Primitive_int.compare);
 
diff --git a/tests/tests/src/bs_poly_mutable_set_test.res b/tests/belt_tests/src/bs_poly_mutable_set_test.res
similarity index 100%
rename from tests/tests/src/bs_poly_mutable_set_test.res
rename to tests/belt_tests/src/bs_poly_mutable_set_test.res
diff --git a/tests/tests/src/bs_poly_set_test.mjs b/tests/belt_tests/src/bs_poly_set_test.mjs
similarity index 96%
rename from tests/tests/src/bs_poly_set_test.mjs
rename to tests/belt_tests/src/bs_poly_set_test.mjs
index 764f7b0fe0c..ae85ac5ca0a 100644
--- a/tests/tests/src/bs_poly_set_test.mjs
+++ b/tests/belt_tests/src/bs_poly_set_test.mjs
@@ -1,14 +1,14 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Id from "@rescript/runtime/lib/es6/Belt_Id.mjs";
-import * as Belt_Set from "@rescript/runtime/lib/es6/Belt_Set.mjs";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Id from "@rescript/belt/lib/es6/src/Belt_Id.mjs";
+import * as Belt_Set from "@rescript/belt/lib/es6/src/Belt_Set.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
-import * as Belt_SetDict from "@rescript/runtime/lib/es6/Belt_SetDict.mjs";
+import * as Belt_SetDict from "@rescript/belt/lib/es6/src/Belt_SetDict.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
-import * as Belt_SortArray from "@rescript/runtime/lib/es6/Belt_SortArray.mjs";
+import * as Belt_SortArray from "@rescript/belt/lib/es6/src/Belt_SortArray.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
 
diff --git a/tests/tests/src/bs_poly_set_test.res b/tests/belt_tests/src/bs_poly_set_test.res
similarity index 100%
rename from tests/tests/src/bs_poly_set_test.res
rename to tests/belt_tests/src/bs_poly_set_test.res
diff --git a/tests/tests/src/bs_queue_test.mjs b/tests/belt_tests/src/bs_queue_test.mjs
similarity index 99%
rename from tests/tests/src/bs_queue_test.mjs
rename to tests/belt_tests/src/bs_queue_test.mjs
index b1551d86463..ba9db353547 100644
--- a/tests/tests/src/bs_queue_test.mjs
+++ b/tests/belt_tests/src/bs_queue_test.mjs
@@ -1,10 +1,10 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
-import * as Belt_MutableQueue from "@rescript/runtime/lib/es6/Belt_MutableQueue.mjs";
+import * as Belt_MutableQueue from "@rescript/belt/lib/es6/src/Belt_MutableQueue.mjs";
 
 function does_raise(f, q) {
   try {
diff --git a/tests/tests/src/bs_queue_test.res b/tests/belt_tests/src/bs_queue_test.res
similarity index 100%
rename from tests/tests/src/bs_queue_test.res
rename to tests/belt_tests/src/bs_queue_test.res
diff --git a/tests/tests/src/bs_set_int_test.mjs b/tests/belt_tests/src/bs_set_int_test.mjs
similarity index 98%
rename from tests/tests/src/bs_set_int_test.mjs
rename to tests/belt_tests/src/bs_set_int_test.mjs
index 2bf1b07cc64..a14053aa637 100644
--- a/tests/tests/src/bs_set_int_test.mjs
+++ b/tests/belt_tests/src/bs_set_int_test.mjs
@@ -1,10 +1,10 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
-import * as Belt_SetInt from "@rescript/runtime/lib/es6/Belt_SetInt.mjs";
+import * as Belt_SetInt from "@rescript/belt/lib/es6/src/Belt_SetInt.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
 
 function setEqArray(s, i) {
diff --git a/tests/tests/src/bs_set_int_test.res b/tests/belt_tests/src/bs_set_int_test.res
similarity index 100%
rename from tests/tests/src/bs_set_int_test.res
rename to tests/belt_tests/src/bs_set_int_test.res
diff --git a/tests/tests/src/bs_stack_test.mjs b/tests/belt_tests/src/bs_stack_test.mjs
similarity index 93%
rename from tests/tests/src/bs_stack_test.mjs
rename to tests/belt_tests/src/bs_stack_test.mjs
index 12061f0c85e..852a1bc015e 100644
--- a/tests/tests/src/bs_stack_test.mjs
+++ b/tests/belt_tests/src/bs_stack_test.mjs
@@ -4,8 +4,8 @@ import * as Mocha from "mocha";
 import * as Test_utils from "./test_utils.mjs";
 import * as Stdlib_Option from "@rescript/runtime/lib/es6/Stdlib_Option.mjs";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
-import * as Belt_MutableQueue from "@rescript/runtime/lib/es6/Belt_MutableQueue.mjs";
-import * as Belt_MutableStack from "@rescript/runtime/lib/es6/Belt_MutableStack.mjs";
+import * as Belt_MutableQueue from "@rescript/belt/lib/es6/src/Belt_MutableQueue.mjs";
+import * as Belt_MutableStack from "@rescript/belt/lib/es6/src/Belt_MutableStack.mjs";
 
 function inOrder(v) {
   let current = v;
diff --git a/tests/tests/src/bs_stack_test.res b/tests/belt_tests/src/bs_stack_test.res
similarity index 100%
rename from tests/tests/src/bs_stack_test.res
rename to tests/belt_tests/src/bs_stack_test.res
diff --git a/tests/tests/src/demo_int_map.mjs b/tests/belt_tests/src/demo_int_map.mjs
similarity index 78%
rename from tests/tests/src/demo_int_map.mjs
rename to tests/belt_tests/src/demo_int_map.mjs
index e4af74e1f0a..f841acdd004 100644
--- a/tests/tests/src/demo_int_map.mjs
+++ b/tests/belt_tests/src/demo_int_map.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_MapInt from "@rescript/runtime/lib/es6/Belt_MapInt.mjs";
+import * as Belt_MapInt from "@rescript/belt/lib/es6/src/Belt_MapInt.mjs";
 
 function test() {
   let m;
diff --git a/tests/tests/src/demo_int_map.res b/tests/belt_tests/src/demo_int_map.res
similarity index 100%
rename from tests/tests/src/demo_int_map.res
rename to tests/belt_tests/src/demo_int_map.res
diff --git a/tests/tests/src/demo_int_map.resi b/tests/belt_tests/src/demo_int_map.resi
similarity index 100%
rename from tests/tests/src/demo_int_map.resi
rename to tests/belt_tests/src/demo_int_map.resi
diff --git a/tests/tests/src/gpr_4265_test.mjs b/tests/belt_tests/src/gpr_4265_test.mjs
similarity index 88%
rename from tests/tests/src/gpr_4265_test.mjs
rename to tests/belt_tests/src/gpr_4265_test.mjs
index 5087dfec67f..bc4b5499adf 100644
--- a/tests/tests/src/gpr_4265_test.mjs
+++ b/tests/belt_tests/src/gpr_4265_test.mjs
@@ -2,7 +2,7 @@
 
 import * as Mocha from "mocha";
 import * as Test_utils from "./test_utils.mjs";
-import * as Belt_MutableMapInt from "@rescript/runtime/lib/es6/Belt_MutableMapInt.mjs";
+import * as Belt_MutableMapInt from "@rescript/belt/lib/es6/src/Belt_MutableMapInt.mjs";
 
 let mockMap = Belt_MutableMapInt.make();
 
diff --git a/tests/tests/src/gpr_4265_test.res b/tests/belt_tests/src/gpr_4265_test.res
similarity index 100%
rename from tests/tests/src/gpr_4265_test.res
rename to tests/belt_tests/src/gpr_4265_test.res
diff --git a/tests/tests/src/hash_test.mjs b/tests/belt_tests/src/hash_test.mjs
similarity index 95%
rename from tests/tests/src/hash_test.mjs
rename to tests/belt_tests/src/hash_test.mjs
index 999dd4539bd..b4a09d8db54 100644
--- a/tests/tests/src/hash_test.mjs
+++ b/tests/belt_tests/src/hash_test.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Hash_utils from "./hash_utils.mjs";
 import * as Test_utils from "./test_utils.mjs";
 
diff --git a/tests/tests/src/hash_test.res b/tests/belt_tests/src/hash_test.res
similarity index 100%
rename from tests/tests/src/hash_test.res
rename to tests/belt_tests/src/hash_test.res
diff --git a/tests/tests/src/hash_utils.mjs b/tests/belt_tests/src/hash_utils.mjs
similarity index 100%
rename from tests/tests/src/hash_utils.mjs
rename to tests/belt_tests/src/hash_utils.mjs
diff --git a/tests/tests/src/hash_utils.res b/tests/belt_tests/src/hash_utils.res
similarity index 100%
rename from tests/tests/src/hash_utils.res
rename to tests/belt_tests/src/hash_utils.res
diff --git a/tests/tests/src/hash_utils.resi b/tests/belt_tests/src/hash_utils.resi
similarity index 100%
rename from tests/tests/src/hash_utils.resi
rename to tests/belt_tests/src/hash_utils.resi
diff --git a/tests/tests/src/inner_unused.mjs b/tests/belt_tests/src/inner_unused.mjs
similarity index 100%
rename from tests/tests/src/inner_unused.mjs
rename to tests/belt_tests/src/inner_unused.mjs
diff --git a/tests/tests/src/inner_unused.res b/tests/belt_tests/src/inner_unused.res
similarity index 100%
rename from tests/tests/src/inner_unused.res
rename to tests/belt_tests/src/inner_unused.res
diff --git a/tests/tests/src/int_map.mjs b/tests/belt_tests/src/int_map.mjs
similarity index 72%
rename from tests/tests/src/int_map.mjs
rename to tests/belt_tests/src/int_map.mjs
index e2f6ec503a7..a9a44bcfeda 100644
--- a/tests/tests/src/int_map.mjs
+++ b/tests/belt_tests/src/int_map.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Id from "@rescript/runtime/lib/es6/Belt_Id.mjs";
-import * as Belt_Map from "@rescript/runtime/lib/es6/Belt_Map.mjs";
+import * as Belt_Id from "@rescript/belt/lib/es6/src/Belt_Id.mjs";
+import * as Belt_Map from "@rescript/belt/lib/es6/src/Belt_Map.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
 
 let cmp = Primitive_object.compare;
diff --git a/tests/tests/src/int_map.res b/tests/belt_tests/src/int_map.res
similarity index 100%
rename from tests/tests/src/int_map.res
rename to tests/belt_tests/src/int_map.res
diff --git a/tests/tests/src/list_test.mjs b/tests/belt_tests/src/list_test.mjs
similarity index 94%
rename from tests/tests/src/list_test.mjs
rename to tests/belt_tests/src/list_test.mjs
index b4b8fa8fbe3..e209f8e996e 100644
--- a/tests/tests/src/list_test.mjs
+++ b/tests/belt_tests/src/list_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
diff --git a/tests/tests/src/list_test.res b/tests/belt_tests/src/list_test.res
similarity index 100%
rename from tests/tests/src/list_test.res
rename to tests/belt_tests/src/list_test.res
diff --git a/tests/tests/src/map_find_test.mjs b/tests/belt_tests/src/map_find_test.mjs
similarity index 85%
rename from tests/tests/src/map_find_test.mjs
rename to tests/belt_tests/src/map_find_test.mjs
index a192f8279f9..1743d6ba2c2 100644
--- a/tests/tests/src/map_find_test.mjs
+++ b/tests/belt_tests/src/map_find_test.mjs
@@ -1,10 +1,10 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
-import * as Belt_MapInt from "@rescript/runtime/lib/es6/Belt_MapInt.mjs";
-import * as Belt_MapString from "@rescript/runtime/lib/es6/Belt_MapString.mjs";
+import * as Belt_MapInt from "@rescript/belt/lib/es6/src/Belt_MapInt.mjs";
+import * as Belt_MapString from "@rescript/belt/lib/es6/src/Belt_MapString.mjs";
 
 let m = Belt_List.reduceReverse({
   hd: [
diff --git a/tests/tests/src/map_find_test.res b/tests/belt_tests/src/map_find_test.res
similarity index 100%
rename from tests/tests/src/map_find_test.res
rename to tests/belt_tests/src/map_find_test.res
diff --git a/tests/belt_tests/src/mocha.mjs b/tests/belt_tests/src/mocha.mjs
new file mode 100644
index 00000000000..d856702bfe6
--- /dev/null
+++ b/tests/belt_tests/src/mocha.mjs
@@ -0,0 +1,2 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+/* This output is empty. Its source's type definitions, externals and/or unused code got optimized away. */
diff --git a/tests/belt_tests/src/mocha.res b/tests/belt_tests/src/mocha.res
new file mode 100644
index 00000000000..a7fc8c9ed39
--- /dev/null
+++ b/tests/belt_tests/src/mocha.res
@@ -0,0 +1,5 @@
+@module("mocha")
+external test: (string, unit => unit) => unit = "test"
+
+@module("mocha")
+external describe: (string, unit => unit) => unit = "describe"
diff --git a/tests/belt_tests/src/node_assert.mjs b/tests/belt_tests/src/node_assert.mjs
new file mode 100644
index 00000000000..d856702bfe6
--- /dev/null
+++ b/tests/belt_tests/src/node_assert.mjs
@@ -0,0 +1,2 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+/* This output is empty. Its source's type definitions, externals and/or unused code got optimized away. */
diff --git a/tests/belt_tests/src/node_assert.res b/tests/belt_tests/src/node_assert.res
new file mode 100644
index 00000000000..3acfbc38ae3
--- /dev/null
+++ b/tests/belt_tests/src/node_assert.res
@@ -0,0 +1,5 @@
+@module("node:assert") external ok: (bool, ~message: string=?) => unit = "ok"
+@module("node:assert")
+external deepEqual: ('a, 'a, ~message: string=?) => unit = "deepStrictEqual"
+@module("node:assert")
+external throws: (unit => 'a, ~error: 'b=?, ~message: string=?) => unit = "throws"
diff --git a/tests/tests/src/rec_module_opt.mjs b/tests/belt_tests/src/rec_module_opt.mjs
similarity index 95%
rename from tests/tests/src/rec_module_opt.mjs
rename to tests/belt_tests/src/rec_module_opt.mjs
index 6f8ec788373..34577f8c6b0 100644
--- a/tests/tests/src/rec_module_opt.mjs
+++ b/tests/belt_tests/src/rec_module_opt.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Id from "@rescript/runtime/lib/es6/Belt_Id.mjs";
+import * as Belt_Id from "@rescript/belt/lib/es6/src/Belt_Id.mjs";
 import * as Primitive_module from "@rescript/runtime/lib/es6/Primitive_module.mjs";
 import * as Primitive_string from "@rescript/runtime/lib/es6/Primitive_string.mjs";
 
diff --git a/tests/tests/src/rec_module_opt.res b/tests/belt_tests/src/rec_module_opt.res
similarity index 100%
rename from tests/tests/src/rec_module_opt.res
rename to tests/belt_tests/src/rec_module_opt.res
diff --git a/tests/tests/src/test_array.mjs b/tests/belt_tests/src/test_array.mjs
similarity index 84%
rename from tests/tests/src/test_array.mjs
rename to tests/belt_tests/src/test_array.mjs
index 02ebf858538..620b3842f69 100644
--- a/tests/tests/src/test_array.mjs
+++ b/tests/belt_tests/src/test_array.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.mjs";
 
 let v = Belt_Array.make(6, 5);
 
diff --git a/tests/tests/src/test_array.res b/tests/belt_tests/src/test_array.res
similarity index 100%
rename from tests/tests/src/test_array.res
rename to tests/belt_tests/src/test_array.res
diff --git a/tests/tests/src/test_for_map.mjs b/tests/belt_tests/src/test_for_map.mjs
similarity index 80%
rename from tests/tests/src/test_for_map.mjs
rename to tests/belt_tests/src/test_for_map.mjs
index 7714e425305..b14e15e2e1e 100644
--- a/tests/tests/src/test_for_map.mjs
+++ b/tests/belt_tests/src/test_for_map.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_MapInt from "@rescript/runtime/lib/es6/Belt_MapInt.mjs";
+import * as Belt_MapInt from "@rescript/belt/lib/es6/src/Belt_MapInt.mjs";
 
 function assertion_test() {
   let m;
diff --git a/tests/tests/src/test_for_map.res b/tests/belt_tests/src/test_for_map.res
similarity index 100%
rename from tests/tests/src/test_for_map.res
rename to tests/belt_tests/src/test_for_map.res
diff --git a/tests/tests/src/test_for_map2.mjs b/tests/belt_tests/src/test_for_map2.mjs
similarity index 81%
rename from tests/tests/src/test_for_map2.mjs
rename to tests/belt_tests/src/test_for_map2.mjs
index 0454f41ee68..adc01d3648c 100644
--- a/tests/tests/src/test_for_map2.mjs
+++ b/tests/belt_tests/src/test_for_map2.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_MapInt from "@rescript/runtime/lib/es6/Belt_MapInt.mjs";
+import * as Belt_MapInt from "@rescript/belt/lib/es6/src/Belt_MapInt.mjs";
 
 function assertion_test() {
   let m;
diff --git a/tests/tests/src/test_for_map2.res b/tests/belt_tests/src/test_for_map2.res
similarity index 100%
rename from tests/tests/src/test_for_map2.res
rename to tests/belt_tests/src/test_for_map2.res
diff --git a/tests/tests/src/test_int_map_find.mjs b/tests/belt_tests/src/test_int_map_find.mjs
similarity index 75%
rename from tests/tests/src/test_int_map_find.mjs
rename to tests/belt_tests/src/test_int_map_find.mjs
index d4729d0be55..24dc3ebac04 100644
--- a/tests/tests/src/test_int_map_find.mjs
+++ b/tests/belt_tests/src/test_int_map_find.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_MapInt from "@rescript/runtime/lib/es6/Belt_MapInt.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_MapInt from "@rescript/belt/lib/es6/src/Belt_MapInt.mjs";
 
 Belt_List.reduceReverse({
   hd: [
diff --git a/tests/tests/src/test_int_map_find.res b/tests/belt_tests/src/test_int_map_find.res
similarity index 100%
rename from tests/tests/src/test_int_map_find.res
rename to tests/belt_tests/src/test_int_map_find.res
diff --git a/tests/tests/src/test_string_map.mjs b/tests/belt_tests/src/test_string_map.mjs
similarity index 87%
rename from tests/tests/src/test_string_map.mjs
rename to tests/belt_tests/src/test_string_map.mjs
index de52cf5de00..e21e0922a4f 100644
--- a/tests/tests/src/test_string_map.mjs
+++ b/tests/belt_tests/src/test_string_map.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_MapString from "@rescript/runtime/lib/es6/Belt_MapString.mjs";
+import * as Belt_MapString from "@rescript/belt/lib/es6/src/Belt_MapString.mjs";
 
 function timing(label, f) {
   console.time(label);
diff --git a/tests/tests/src/test_string_map.res b/tests/belt_tests/src/test_string_map.res
similarity index 100%
rename from tests/tests/src/test_string_map.res
rename to tests/belt_tests/src/test_string_map.res
diff --git a/tests/belt_tests/src/test_utils.mjs b/tests/belt_tests/src/test_utils.mjs
new file mode 100644
index 00000000000..8dbe369ec5c
--- /dev/null
+++ b/tests/belt_tests/src/test_utils.mjs
@@ -0,0 +1,28 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+import * as Nodeassert from "node:assert";
+
+function ok(loc, a) {
+  Nodeassert.ok(a, loc);
+}
+
+function eq(loc, a, b) {
+  Nodeassert.deepStrictEqual(a, b, loc);
+}
+
+function throws(loc, f) {
+  Nodeassert.throws(f, undefined, loc);
+}
+
+function approxEq(loc, threshold, a, b) {
+  let diff = Math.abs(a - b);
+  Nodeassert.ok(diff <= threshold, loc);
+}
+
+export {
+  ok,
+  eq,
+  throws,
+  approxEq,
+}
+/* node:assert Not a pure module */
diff --git a/tests/belt_tests/src/test_utils.res b/tests/belt_tests/src/test_utils.res
new file mode 100644
index 00000000000..a713650a8f8
--- /dev/null
+++ b/tests/belt_tests/src/test_utils.res
@@ -0,0 +1,8 @@
+let ok = (loc, a) => Node_assert.ok(a, ~message=loc)
+let eq = (loc, a, b) => Node_assert.deepEqual(a, b, ~message=loc)
+let throws = (loc, f) => Node_assert.throws(f, ~message=loc)
+
+let approxEq = (loc, threshold, a, b) => {
+  let diff = Math.abs(a -. b)
+  Node_assert.ok(diff <= threshold, ~message=loc)
+}
diff --git a/tests/tests/src/ticker.mjs b/tests/belt_tests/src/ticker.mjs
similarity index 96%
rename from tests/tests/src/ticker.mjs
rename to tests/belt_tests/src/ticker.mjs
index 2814daec777..7303100f71e 100644
--- a/tests/tests/src/ticker.mjs
+++ b/tests/belt_tests/src/ticker.mjs
@@ -1,11 +1,11 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Float from "@rescript/runtime/lib/es6/Belt_Float.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.mjs";
+import * as Belt_Float from "@rescript/belt/lib/es6/src/Belt_Float.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
-import * as Belt_Option from "@rescript/runtime/lib/es6/Belt_Option.mjs";
+import * as Belt_Option from "@rescript/belt/lib/es6/src/Belt_Option.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
-import * as Belt_MapString from "@rescript/runtime/lib/es6/Belt_MapString.mjs";
+import * as Belt_MapString from "@rescript/belt/lib/es6/src/Belt_MapString.mjs";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function split(delim, s) {
diff --git a/tests/tests/src/ticker.res b/tests/belt_tests/src/ticker.res
similarity index 100%
rename from tests/tests/src/ticker.res
rename to tests/belt_tests/src/ticker.res
diff --git a/tests/build_tests/super_errors/input.js b/tests/build_tests/super_errors/input.js
index 8b8385dbcbe..25f58eff42d 100644
--- a/tests/build_tests/super_errors/input.js
+++ b/tests/build_tests/super_errors/input.js
@@ -15,7 +15,19 @@ const fixtures = readdirSync(path.join(import.meta.dirname, "fixtures"))
   .filter(fileName => path.extname(fileName) === ".res")
   .sort();
 
-const prefix = ["-w", "+A", "-bs-jsx", "4"];
+const beltLib = path.join(
+  import.meta.dirname,
+  "..",
+  "..",
+  "..",
+  "packages",
+  "@rescript",
+  "belt",
+  "lib",
+  "ocaml",
+);
+
+const prefix = ["-w", "+A", "-bs-jsx", "4", "-I", beltLib];
 
 const updateTests = process.argv[2] === "update";
 
diff --git a/tests/commonjs_tests/package.json b/tests/commonjs_tests/package.json
index 65eaa8d6ed9..69b69f4589f 100644
--- a/tests/commonjs_tests/package.json
+++ b/tests/commonjs_tests/package.json
@@ -1,5 +1,9 @@
 {
   "name": "rescript-commonjs-tests",
   "private": true,
-  "type": "commonjs"
+  "type": "commonjs",
+  "dependencies": {
+    "@rescript/belt": "workspace:^",
+    "rescript": "workspace:^"
+  }
 }
diff --git a/tests/commonjs_tests/rescript.json b/tests/commonjs_tests/rescript.json
index 07961edebb5..99881fc3f4f 100644
--- a/tests/commonjs_tests/rescript.json
+++ b/tests/commonjs_tests/rescript.json
@@ -1,5 +1,6 @@
 {
   "name": "rescript-commonjs-tests",
+  "dependencies": ["@rescript/belt"],
   "sources": [
     {
       "dir": "src",
diff --git a/tests/commonjs_tests/src/belt_import.js b/tests/commonjs_tests/src/belt_import.js
index 1973f2b395a..7cf8919fd11 100644
--- a/tests/commonjs_tests/src/belt_import.js
+++ b/tests/commonjs_tests/src/belt_import.js
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 'use strict';
 
-let Belt_MapInt = require("@rescript/runtime/lib/js/Belt_MapInt.cjs");
+let Belt_MapInt = require("@rescript/belt/src/Belt_MapInt.js");
 
 let f = Belt_MapInt.get;
 
diff --git a/tests/docstring_tests/DocTest.res b/tests/docstring_tests/DocTest.res
index f806d9d0176..34f84372767 100644
--- a/tests/docstring_tests/DocTest.res
+++ b/tests/docstring_tests/DocTest.res
@@ -51,26 +51,35 @@ let extractDocFromFile = async file => {
 
 let batchSize = OS.cpus()->Array.length
 
-let runtimePath = Path.join(["packages", "@rescript", "runtime"])
+let docPaths = [
+  Path.join(["packages", "@rescript", "runtime"]),
+  Path.join(["packages", "@rescript", "belt", "src"]),
+]
 
 let extractExamples = async () => {
-  let files = Fs.readdirSync(runtimePath)
-
-  let docFiles = files->Array.filter(f =>
-    switch f {
-    // Ignore Js modules and RescriptTools for now
-    | f if f->String.startsWith("Js") || f->String.startsWith("RescriptTools") => false
-    | f if f->String.endsWith(".resi") => true
-    | f if f->String.endsWith(".res") && !(files->Array.includes(f ++ "i")) => true
-    | _ => false
-    }
-  )
+  let docFiles = docPaths->Array.flatMap(docPath => {
+    let files = Fs.readdirSync(docPath)
+
+    files
+    ->Array.filter(f =>
+      switch f {
+      // Ignore Js modules and RescriptTools for now
+      | f if f->String.startsWith("Js") || f->String.startsWith("RescriptTools") => false
+      | f if f->String.endsWith(".resi") => true
+      | f if f->String.endsWith(".res") && !(files->Array.includes(f ++ "i")) => true
+      | _ => false
+      }
+    )
+    ->Array.map(f => Path.join([docPath, f]))
+  })
 
-  Console.log(`Extracting examples from ${docFiles->Array.length->Int.toString} runtime files...`)
+  Console.log(
+    `Extracting examples from ${docFiles->Array.length->Int.toString} runtime and Belt files...`,
+  )
 
   let examples = []
-  await docFiles->ArrayUtils.forEachAsyncInBatches(~batchSize, async f => {
-    let doc = await extractDocFromFile(Path.join([runtimePath, f]))
+  await docFiles->ArrayUtils.forEachAsyncInBatches(~batchSize, async file => {
+    let doc = await extractDocFromFile(file)
     // TODO: Should this be a flag in the actual command instead, to only include code blocks with tests?
     examples->Array.pushMany(doc->Array.filter(d => d.code->String.includes("assertEqual(")))
   })
diff --git a/tests/docstring_tests/DocTest.res.js b/tests/docstring_tests/DocTest.res.js
index c372acd3dc5..ced1ac1dac7 100644
--- a/tests/docstring_tests/DocTest.res.js
+++ b/tests/docstring_tests/DocTest.res.js
@@ -58,25 +58,30 @@ async function extractDocFromFile(file) {
 
 let batchSize = Nodeos.cpus().length;
 
-let runtimePath = Nodepath.join("packages", "@rescript", "runtime");
+let docPaths = [
+  Nodepath.join("packages", "@rescript", "runtime"),
+  Nodepath.join("packages", "@rescript", "belt", "src")
+];
 
 async function extractExamples() {
-  let files = Nodefs.readdirSync(runtimePath);
-  let docFiles = files.filter(f => {
-    if (f.startsWith("Js") || f.startsWith("RescriptTools")) {
-      return false;
-    } else if (f.endsWith(".resi")) {
-      return true;
-    } else if (f.endsWith(".res")) {
-      return !files.includes(f + "i");
-    } else {
-      return false;
-    }
+  let docFiles = docPaths.flatMap(docPath => {
+    let files = Nodefs.readdirSync(docPath);
+    return files.filter(f => {
+      if (f.startsWith("Js") || f.startsWith("RescriptTools")) {
+        return false;
+      } else if (f.endsWith(".resi")) {
+        return true;
+      } else if (f.endsWith(".res")) {
+        return !files.includes(f + "i");
+      } else {
+        return false;
+      }
+    }).map(f => Nodepath.join(docPath, f));
   });
-  console.log(`Extracting examples from ` + docFiles.length.toString() + ` runtime files...`);
+  console.log(`Extracting examples from ` + docFiles.length.toString() + ` runtime and Belt files...`);
   let examples = [];
-  await ArrayUtils.forEachAsyncInBatches(docFiles, batchSize, async f => {
-    let doc = await extractDocFromFile(Nodepath.join(runtimePath, f));
+  await ArrayUtils.forEachAsyncInBatches(docFiles, batchSize, async file => {
+    let doc = await extractDocFromFile(file);
     examples.push(...doc.filter(d => d.code.includes("assertEqual(")));
   });
   examples.sort((a, b) => Primitive_string.compare(a.id, b.id));
diff --git a/tests/docstring_tests/package.json b/tests/docstring_tests/package.json
index bf66f5bc3e0..0d291141595 100644
--- a/tests/docstring_tests/package.json
+++ b/tests/docstring_tests/package.json
@@ -8,6 +8,7 @@
     "dev": "rescript -w"
   },
   "dependencies": {
+    "@rescript/belt": "workspace:^",
     "@rescript/react": "workspace:^",
     "rescript": "workspace:^"
   }
diff --git a/tests/docstring_tests/rescript.json b/tests/docstring_tests/rescript.json
index 19bad773ee7..337c4724896 100644
--- a/tests/docstring_tests/rescript.json
+++ b/tests/docstring_tests/rescript.json
@@ -3,6 +3,7 @@
   "sources": {
     "dir": "."
   },
+  "dependencies": ["@rescript/belt"],
   "package-specs": {
     "module": "esmodule",
     "in-source": true
diff --git a/tests/gentype_tests/typescript-react-example/package.json b/tests/gentype_tests/typescript-react-example/package.json
index 25429abbd85..dca99323005 100644
--- a/tests/gentype_tests/typescript-react-example/package.json
+++ b/tests/gentype_tests/typescript-react-example/package.json
@@ -8,6 +8,7 @@
     "typecheck": "tsc"
   },
   "dependencies": {
+    "@rescript/belt": "workspace:^",
     "@rescript/react": "workspace:^",
     "react": "^19.2.8",
     "react-dom": "^19.2.8",
diff --git a/tests/gentype_tests/typescript-react-example/rescript.json b/tests/gentype_tests/typescript-react-example/rescript.json
index 00ecbd68bad..e1b9ea4efdb 100644
--- a/tests/gentype_tests/typescript-react-example/rescript.json
+++ b/tests/gentype_tests/typescript-react-example/rescript.json
@@ -18,7 +18,7 @@
   "name": "@tests/gentype-react-example",
   "compiler-flags": [],
   "jsx": { "version": 4 },
-  "dependencies": ["@rescript/react"],
+  "dependencies": ["@rescript/belt", "@rescript/react"],
   "sources": [
     {
       "dir": "src",
diff --git a/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res.js b/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res.js
index 624a05dd831..b3685b361d1 100644
--- a/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res.js
+++ b/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res.js
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.res.js";
 
 function fromArray(a) {
   return a.slice(0);
diff --git a/tests/gentype_tests/typescript-react-example/src/Records.res.js b/tests/gentype_tests/typescript-react-example/src/Records.res.js
index fb6b21fa820..cc58487d4db 100644
--- a/tests/gentype_tests/typescript-react-example/src/Records.res.js
+++ b/tests/gentype_tests/typescript-react-example/src/Records.res.js
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
-import * as Belt_Option from "@rescript/runtime/lib/es6/Belt_Option.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.res.js";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.res.js";
+import * as Belt_Option from "@rescript/belt/lib/es6/src/Belt_Option.res.js";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function computeArea(param) {
diff --git a/tests/gentype_tests/typescript-react-example/src/TestImmutableArray.res.js b/tests/gentype_tests/typescript-react-example/src/TestImmutableArray.res.js
index cc796d2b9c3..07280d49f1f 100644
--- a/tests/gentype_tests/typescript-react-example/src/TestImmutableArray.res.js
+++ b/tests/gentype_tests/typescript-react-example/src/TestImmutableArray.res.js
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Belt_Array from "@rescript/belt/lib/es6/src/Belt_Array.res.js";
 import * as ImmutableArray from "./ImmutableArray.res.js";
 
 function testImmutableArrayGet(arr) {
diff --git a/tests/gentype_tests/typescript-react-example/src/Variants.gen.tsx b/tests/gentype_tests/typescript-react-example/src/Variants.gen.tsx
index 3b2b65d60d0..de6f167653d 100644
--- a/tests/gentype_tests/typescript-react-example/src/Variants.gen.tsx
+++ b/tests/gentype_tests/typescript-react-example/src/Variants.gen.tsx
@@ -45,6 +45,10 @@ export type result3<a,b> =
     { TAG: "Ok"; _0: a }
   | { TAG: "Error"; _0: b };
 
+export type result4<a,b> = 
+    { TAG: "Ok"; _0: a }
+  | { TAG: "Error"; _0: b };
+
 export const isWeekend: (x:weekday) => boolean = VariantsJS.isWeekend as any;
 
 export const monday: "monday" = VariantsJS.monday as any;
diff --git a/tests/gentype_tests/typescript-react-example/src/Variants.res b/tests/gentype_tests/typescript-react-example/src/Variants.res
index 9b1fb0e6724..17434db6b6d 100644
--- a/tests/gentype_tests/typescript-react-example/src/Variants.res
+++ b/tests/gentype_tests/typescript-react-example/src/Variants.res
@@ -101,7 +101,9 @@ type result1<'a, 'b> =
 
 @genType type result2<'a, 'b> = result<'a, 'b>
 
-@genType type result3<'a, 'b> = Belt.Result.t<'a, 'b>
+@genType type result3<'a, 'b> = Stdlib.Result.t<'a, 'b>
+
+@genType type result4<'a, 'b> = Belt.Result.t<'a, 'b>
 
 @genType let restResult1 = (x: result1<int, string>) => x
 
diff --git a/tests/gentype_tests/typescript-react-example/src/nested/Tuples.res.js b/tests/gentype_tests/typescript-react-example/src/nested/Tuples.res.js
index c26755f2520..eb4b380db0c 100644
--- a/tests/gentype_tests/typescript-react-example/src/nested/Tuples.res.js
+++ b/tests/gentype_tests/typescript-react-example/src/nested/Tuples.res.js
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Option from "@rescript/runtime/lib/es6/Belt_Option.mjs";
+import * as Belt_Option from "@rescript/belt/lib/es6/src/Belt_Option.res.js";
 
 function testTuple(param) {
   return param[0] + param[1] | 0;
diff --git a/tests/gentype_tests/typescript-react-example/src/nested/Types.res.js b/tests/gentype_tests/typescript-react-example/src/nested/Types.res.js
index 0ec0a547c38..c05d7b019d4 100644
--- a/tests/gentype_tests/typescript-react-example/src/nested/Types.res.js
+++ b/tests/gentype_tests/typescript-react-example/src/nested/Types.res.js
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Option from "@rescript/runtime/lib/es6/Belt_Option.mjs";
+import * as Belt_List from "@rescript/belt/lib/es6/src/Belt_List.res.js";
+import * as Belt_Option from "@rescript/belt/lib/es6/src/Belt_Option.res.js";
 
 function swap(tree) {
   return {
diff --git a/tests/package_tests/installation_test/rescript-with-belt.json b/tests/package_tests/installation_test/rescript-with-belt.json
new file mode 100644
index 00000000000..8cde462bc2b
--- /dev/null
+++ b/tests/package_tests/installation_test/rescript-with-belt.json
@@ -0,0 +1,13 @@
+{
+  "name": "install-test",
+  "sources": {
+    "dir": "src",
+    "subdirs": true
+  },
+  "package-specs": {
+    "module": "esmodule",
+    "in-source": true,
+    "suffix": ".mjs"
+  },
+  "dependencies": ["@rescript/belt"]
+}
diff --git a/tests/package_tests/installation_test/rescript.json b/tests/package_tests/installation_test/rescript.json
index fd6dfe79cd4..dbedc995627 100644
--- a/tests/package_tests/installation_test/rescript.json
+++ b/tests/package_tests/installation_test/rescript.json
@@ -7,6 +7,6 @@
   "package-specs": {
     "module": "esmodule",
     "in-source": true,
-    "suffix": ".res.js"
+    "suffix": ".mjs"
   }
 }
diff --git a/tests/package_tests/installation_test/src/BeltTest.res.txt b/tests/package_tests/installation_test/src/BeltTest.res.txt
new file mode 100644
index 00000000000..d926c78ad69
--- /dev/null
+++ b/tests/package_tests/installation_test/src/BeltTest.res.txt
@@ -0,0 +1,6 @@
+let values = Belt.Array.make(3, 42)
+
+switch Belt.Array.get(values, 1) {
+| Some(42) => Console.log("Belt runtime dependency resolved")
+| _ => JsError.throwWithMessage("Unexpected Belt.Array result")
+}
diff --git a/tests/package_tests/installation_test/src/Test.res b/tests/package_tests/installation_test/src/Test.res
index 2bb95f0a6ee..3eb42775186 100644
--- a/tests/package_tests/installation_test/src/Test.res
+++ b/tests/package_tests/installation_test/src/Test.res
@@ -1 +1,12 @@
 Console.log("Hello, world!")
+
+let middleArray = [2, 3]
+let endArray = [5]
+let array = [1, ...middleArray, 4, ...endArray]
+
+let middleList = list{2, 3}
+let endList = list{5}
+let list = list{1, ...middleList, 4, ...endList}
+
+assert(array == [1, 2, 3, 4, 5])
+assert(list == list{1, 2, 3, 4, 5})
diff --git a/tests/syntax_tests/data/parsing/grammar/expressions/expected/array.res.txt b/tests/syntax_tests/data/parsing/grammar/expressions/expected/array.res.txt
index 3c21a9a9ab2..af12c028724 100644
--- a/tests/syntax_tests/data/parsing/grammar/expressions/expected/array.res.txt
+++ b/tests/syntax_tests/data/parsing/grammar/expressions/expected/array.res.txt
@@ -1,8 +1,8 @@
 let x = [|1;2;3|]
 let x = [|1;2;3|]
 let x = [|(1 : int);(2 : int);(3 : int)|]
-let x = ((Belt.Array.concatMany)[@res.spread ]) [|[|4;5|];y|]
-let x = ((Belt.Array.concatMany)[@res.spread ]) [|[|4;5|];y;[|7|];y|]
-let x = ((Belt.Array.concatMany)[@res.spread ]) [|[|4;5|];(y : int array)|]
-let x = ((Belt.Array.concatMany)[@res.spread ]) [|[|4;5;k|];y|]
-let x = ((Belt.Array.concatMany)[@res.spread ]) [|y|]
\ No newline at end of file
+let x = ((Primitive_array.spread)[@res.spread ]) [|[|4;5|];y|]
+let x = ((Primitive_array.spread)[@res.spread ]) [|[|4;5|];y;[|7|];y|]
+let x = ((Primitive_array.spread)[@res.spread ]) [|[|4;5|];(y : int array)|]
+let x = ((Primitive_array.spread)[@res.spread ]) [|[|4;5;k|];y|]
+let x = ((Primitive_array.spread)[@res.spread ]) [|y|]
\ No newline at end of file
diff --git a/tests/syntax_tests/data/parsing/grammar/expressions/expected/list.res.txt b/tests/syntax_tests/data/parsing/grammar/expressions/expected/list.res.txt
index 4205548d1ee..8506759923e 100644
--- a/tests/syntax_tests/data/parsing/grammar/expressions/expected/list.res.txt
+++ b/tests/syntax_tests/data/parsing/grammar/expressions/expected/list.res.txt
@@ -3,5 +3,5 @@ let x = [1; 2; 3]
 let x = [1; 2; 3]
 let x = [(1 : int); (2 : int); (3 : int)]
 let x = 4 :: 5 :: y
-let x = ((Belt.List.concatMany)[@res.spread ]) [|(1 :: x);(2 :: 3 :: x)|]
+let x = ((Primitive_list.spread)[@res.spread ]) [|(1 :: x);(2 :: 3 :: x)|]
 let x = 1 :: 2 :: (y : int list)
\ No newline at end of file
diff --git a/tests/syntax_tests/data/parsing/recovery/expression/expected/list.res.txt b/tests/syntax_tests/data/parsing/recovery/expression/expected/list.res.txt
index 3b8e3ad5871..efdedd7aa6c 100644
--- a/tests/syntax_tests/data/parsing/recovery/expression/expected/list.res.txt
+++ b/tests/syntax_tests/data/parsing/recovery/expression/expected/list.res.txt
@@ -42,7 +42,8 @@ let flags =
           ((match items with
             | [|{js|-pp|js};_ppFlag;rest|] -> loop rest
             | [|x;rest|] ->
-                ((Belt.Array.concatMany)[@res.spread ]) [|[|x|];(loop rest)|]
+                ((Primitive_array.spread)[@res.spread ])
+                  [|[|x|];(loop rest)|]
             | [||] -> [||])
           [@res.braces ]) in
         (loop parts) -> (String.concat {js| |js}))
diff --git a/tests/tests/src/Import.mjs b/tests/tests/src/Import.mjs
index 9107520fe8f..fceabb7d2e2 100644
--- a/tests/tests/src/Import.mjs
+++ b/tests/tests/src/Import.mjs
@@ -2,11 +2,11 @@
 
 
 async function eachIntAsync(list, f) {
-  return (await import("@rescript/runtime/lib/es6/Belt_List.mjs").then(m => m.forEach))(list, f);
+  return (await import("@rescript/runtime/lib/es6/Stdlib_List.mjs").then(m => m.forEach))(list, f);
 }
 
 function eachIntLazy(list, f) {
-  return import("@rescript/runtime/lib/es6/Belt_List.mjs").then(m => m.forEach).then(each => Promise.resolve(each(list, f)));
+  return import("@rescript/runtime/lib/es6/Stdlib_List.mjs").then(m => m.forEach).then(each => Promise.resolve(each(list, f)));
 }
 
 eachIntLazy({
@@ -35,13 +35,13 @@ eachIntAsync({
   console.log("async", n);
 });
 
-let beltAsModule = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
+let listAsModule = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
 
-let M = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
+let M = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
 
-let N0 = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
+let N0 = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
 
-let O = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
+let O = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
 
 let N1_each = O.forEach;
 
@@ -50,7 +50,7 @@ let N1 = {
   each: N1_each
 };
 
-let N2 = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
+let N2 = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
 
 let N_each = N2.forEach;
 
@@ -61,21 +61,21 @@ let N = {
   each: N_each
 };
 
-let M0 = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
+let M0 = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
 
-let M1 = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
+let M1 = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
 
 async function f() {
-  return (await import("@rescript/runtime/lib/es6/Belt_List.mjs")).forEach;
+  return (await import("@rescript/runtime/lib/es6/Stdlib_List.mjs")).forEach;
 }
 
 async function f1() {
-  return (await import("@rescript/runtime/lib/es6/Belt_List.mjs")).forEach;
+  return (await import("@rescript/runtime/lib/es6/Stdlib_List.mjs")).forEach;
 }
 
 async function f2() {
-  let M3 = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
-  let M4 = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
+  let M3 = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
+  let M4 = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
   return [
     M3.forEach,
     M4.forEach
@@ -83,8 +83,8 @@ async function f2() {
 }
 
 async function f3() {
-  let M3 = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
-  let M4 = await import("@rescript/runtime/lib/es6/Belt_List.mjs");
+  let M3 = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
+  let M4 = await import("@rescript/runtime/lib/es6/Stdlib_List.mjs");
   return [
     M3.forEach,
     M4.forEach
@@ -92,41 +92,51 @@ async function f3() {
 }
 
 async function f4() {
-  return (await import("@rescript/runtime/lib/es6/Belt_Array.mjs")).forEach;
+  await import("@rescript/runtime/lib/es6/Stdlib_Array.mjs");
+  return (prim0, prim1) => {
+    prim0.forEach(prim1);
+  };
 }
 
 async function f5() {
-  let A = await import("@rescript/runtime/lib/es6/Belt_Array.mjs");
-  let O = await import("@rescript/runtime/lib/es6/Belt_Option.mjs");
+  await import("@rescript/runtime/lib/es6/Stdlib_Array.mjs");
+  let O = await import("@rescript/runtime/lib/es6/Stdlib_Option.mjs");
   return [
-    A.forEach,
+    (prim0, prim1) => {
+      prim0.forEach(prim1);
+    },
     O.forEach
   ];
 }
 
 async function f6() {
-  let MS = await import("@rescript/runtime/lib/es6/Belt_MapString.mjs");
-  let A = await import("@rescript/runtime/lib/es6/Belt_Array.mjs");
+  await import("@rescript/runtime/lib/es6/Stdlib_Set.mjs");
+  let b = (prim0, prim1) => {
+    prim0.forEach(prim1);
+  };
+  await import("@rescript/runtime/lib/es6/Stdlib_Array.mjs");
   return [
     0,
-    MS.forEach,
-    A.forEach
+    b,
+    (prim0, prim1) => {
+      prim0.forEach(prim1);
+    }
   ];
 }
 
 async function f7() {
-  await import("@rescript/runtime/lib/es6/Belt_MapInt.mjs");
+  await import("@rescript/runtime/lib/es6/Stdlib_Int.mjs");
   return 1;
 }
 
 async function f8() {
-  await import("@rescript/runtime/lib/es6/Belt_MutableQueue.mjs");
+  await import("@rescript/runtime/lib/es6/Stdlib_Set.mjs");
   return 1;
 }
 
 async function f9(value) {
   if (value !== undefined) {
-    await import("@rescript/runtime/lib/es6/Belt_HashMapInt.mjs");
+    await import("@rescript/runtime/lib/es6/Stdlib_Math.mjs");
     return;
   }
 }
@@ -140,7 +150,7 @@ let each2 = O.forEach;
 export {
   eachIntAsync,
   eachIntLazy,
-  beltAsModule,
+  listAsModule,
   M,
   N,
   M0,
diff --git a/tests/tests/src/Import.res b/tests/tests/src/Import.res
index d3ec0107235..3dcb159d339 100644
--- a/tests/tests/src/Import.res
+++ b/tests/tests/src/Import.res
@@ -1,105 +1,105 @@
 let eachIntAsync = async (list: list<int>, f: int => unit) => {
-  list->(await import(Belt.List.forEach))(f)
+  list->(await import(List.forEach))(f)
 }
 
 let eachIntLazy = (list: list<int>, f: int => unit) =>
-  Promise.then(import(Belt.List.forEach), each => list->each(f)->Promise.resolve)
+  Promise.then(import(List.forEach), each => list->each(f)->Promise.resolve)
 
 let _ = list{1, 2, 3}->eachIntLazy(n => Console.log2("lazy", n))
 let _ = list{1, 2, 3}->eachIntAsync(n => Console.log2("async", n))
 
-module type BeltList = module type of Belt.List
-let beltAsModule = await import(module(Belt.List: BeltList))
+module type ListType = module type of List
+let listAsModule = await import(module(List: ListType))
 
-// module type BeltList0 = module type of Belt.List
-// module M = unpack(@res.await import(module(Belt.List: BeltList0)))
-module M = await Belt.List
+// module type ListType0 = module type of List
+// module M = unpack(@res.await import(module(List: ListType0)))
+module M = await List
 let each = M.forEach
 
 module N = {
-  module N0 = await Belt.List
+  module N0 = await List
   let each = N0.forEach
 
   module N1 = {
-    module O = await Belt.List
+    module O = await List
     let each = O.forEach
   }
 
-  module N2 = await Belt.List
+  module N2 = await List
   let each = N2.forEach
 }
 
-module M0 = await Belt.List
+module M0 = await List
 let each = M0.forEach
 
-module M1 = await Belt.List
+module M1 = await List
 let each = M1.forEach
 
 module M2 = N.N1.O
 let each2 = M2.forEach
 
 let f = async () => {
-  module M3 = await Belt.List
+  module M3 = await List
   M3.forEach
 }
 
 let f1 = async () => {
-  module M3 = await (Belt.List: BeltList)
+  module M3 = await (List: ListType)
   M3.forEach
 }
 
 let f2 = async () => {
-  module M3 = await (Belt.List: BeltList)
-  module M4 = await (Belt.List: BeltList)
+  module M3 = await (List: ListType)
+  module M4 = await (List: ListType)
   (M3.forEach, M4.forEach)
 }
 
 let f3 = async () => {
-  module M3 = await Belt.List
-  module M4 = await Belt.List
+  module M3 = await List
+  module M4 = await List
   (M3.forEach, M4.forEach)
 }
 
 let f4 = async () => {
-  module A = await Belt.Array
+  module A = await Array
   A.forEach
 }
 
 let f5 = async () => {
-  module A = await Belt.Array
-  module O = await Belt.Option
+  module A = await Array
+  module O = await Option
   (A.forEach, O.forEach)
 }
 
 let f6 = async () => {
   let a = 0
   and b = {
-    module MS = await Belt.Map.String
+    module MS = await Set
     MS.forEach
   }
-  module A = await Belt.Array
+  module A = await Array
   (a, b, A.forEach)
 }
 
 let f7 = async () => {
   if true {
-    module MI = await Belt.Map.Int
+    module MI = await Int
     1
   } else {
-    module MI = await Belt.Map.Dict
+    module MI = await Dict
     0
   }
 }
 
 let f8 = async (): int => {
-  module MQ = await Belt.MutableQueue
+  module S = await Set
   1
 }
 
 let f9 = async value => {
   switch value {
   | Some(_) =>
-    module HashMapInt = await Belt.HashMap.Int
+    module MathModule = await Math
     ()
   | None => ()
   }
diff --git a/tests/tests/src/UntaggedVariants.mjs b/tests/tests/src/UntaggedVariants.mjs
index ade41daad7f..29c3349792e 100644
--- a/tests/tests/src/UntaggedVariants.mjs
+++ b/tests/tests/src/UntaggedVariants.mjs
@@ -1,6 +1,5 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function classify(x) {
@@ -473,7 +472,7 @@ async function classify$10(a) {
     return;
   } else {
     if (Array.isArray(a)) {
-      console.log(Belt_Array.joinWith(a, "-", x => x));
+      console.log(a.join("-"));
       return;
     }
     if (a instanceof Promise) {
@@ -497,7 +496,7 @@ let Arr = {
 
 async function classifyAll(t) {
   if (Array.isArray(t)) {
-    console.log(Belt_Array.joinWith(t, "-", x => x));
+    console.log(t.join("-"));
     return;
   }
   if (t instanceof Promise) {
diff --git a/tests/tests/src/UntaggedVariants.res b/tests/tests/src/UntaggedVariants.res
index 822b0b0ce4f..1d0eafe49fd 100644
--- a/tests/tests/src/UntaggedVariants.res
+++ b/tests/tests/src/UntaggedVariants.res
@@ -375,7 +375,7 @@ module Arr = {
 
   let classify = async (a: arr) =>
     switch a {
-    | Array(arr) => Console.log(arr->Belt.Array.joinWith("-", x => x))
+    | Array(arr) => Console.log(arr->Array.joinWith("-"))
     | String(s) => Console.log(s)
     | Promise(p) => Console.log(await p)
     | Object({userName}) => Console.log(userName)
@@ -425,7 +425,7 @@ module AllInstanceofTypes = {
     | Object({userName}) => Console.log(userName)
     | Date(date) => Console.log(date->Date.toString)
     | RegExp(re) => Console.log(re->RegExp.test("test"))
-    | Array(arr) => Console.log(arr->Belt.Array.joinWith("-", x => x))
+    | Array(arr) => Console.log(arr->Array.joinWith("-"))
     | File(file) => Console.log(file->fileName)
     | Blob(blob) => Console.log(blob->blobSize)
     | ArrayBuffer(_) => Console.log("ArrayBuffer")
diff --git a/tests/tests/src/a.res b/tests/tests/src/a.res
index d6dfa0c8689..6a68ebedef1 100644
--- a/tests/tests/src/a.res
+++ b/tests/tests/src/a.res
@@ -20,8 +20,6 @@ include (
       let add = (x, y) => x + y
     })
 
-    open Belt
-
     include List
     module N = List
     let v = N.length
diff --git a/tests/tests/src/alias_default_value_test.mjs b/tests/tests/src/alias_default_value_test.mjs
index 714b76ab98a..e6024d44a48 100644
--- a/tests/tests/src/alias_default_value_test.mjs
+++ b/tests/tests/src/alias_default_value_test.mjs
@@ -72,7 +72,7 @@ function Alias_default_value_test$C7(props) {
   let username = props.username;
   let count = props.count;
   let times = count !== 1 ? (
-      count !== 2 ? String(count) + " times" : "twice"
+      count !== 2 ? count.toString() + " times" : "twice"
     ) : "once";
   let name = username !== undefined && username !== "" ? username : "Anonymous";
   return `Hello ` + name + `, you clicked me ` + times;
diff --git a/tests/tests/src/alias_default_value_test.res b/tests/tests/src/alias_default_value_test.res
index f5837af7a62..032b1e75d4e 100644
--- a/tests/tests/src/alias_default_value_test.res
+++ b/tests/tests/src/alias_default_value_test.res
@@ -52,7 +52,7 @@ module C7 = {
       let times = switch count {
       | 1 => "once"
       | 2 => "twice"
-      | n => Belt.Int.toString(n) ++ " times"
+      | n => Int.toString(n) ++ " times"
       }
 
       let name = switch username {
diff --git a/tests/tests/src/async_await.mjs b/tests/tests/src/async_await.mjs
index c8059798bad..a262cdc0d22 100644
--- a/tests/tests/src/async_await.mjs
+++ b/tests/tests/src/async_await.mjs
@@ -35,11 +35,11 @@ async function f(value) {
 }
 
 async function f0() {
-  return (await import("@rescript/runtime/lib/es6/Belt_Option.mjs")).forEach;
+  return (await import("@rescript/runtime/lib/es6/Stdlib_Option.mjs")).forEach;
 }
 
 async function f1() {
-  return (await import("@rescript/runtime/lib/es6/Belt_Option.mjs")).forEach;
+  return (await import("@rescript/runtime/lib/es6/Stdlib_Option.mjs")).forEach;
 }
 
 export {
diff --git a/tests/tests/src/async_await.res b/tests/tests/src/async_await.res
index 6fdeba0d6a0..26f1863e23f 100644
--- a/tests/tests/src/async_await.res
+++ b/tests/tests/src/async_await.res
@@ -19,14 +19,14 @@ let f = async (type input, value: input) => {
   await Promise.resolve(1)
 }
 
-module type MT = module type of Belt.Option
+module type MT = module type of Option
 
 let f0 = async () => {
-  module O = await Belt.Option
+  module O = await Option
   O.forEach
 }
 
 let f1 = async () => {
-  module O: MT = await Belt.Option
+  module O: MT = await Option
   O.forEach
 }
diff --git a/tests/tests/src/bdd.mjs b/tests/tests/src/bdd.mjs
index 7dfffc0f31e..bbdc679fa72 100644
--- a/tests/tests/src/bdd.mjs
+++ b/tests/tests/src/bdd.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 function $$eval(_bdd, vars) {
   while (true) {
@@ -38,7 +38,7 @@ let sz_1 = {
 };
 
 let htab = {
-  contents: Belt_Array.make(sz_1.contents + 1 | 0, /* [] */0)
+  contents: Stdlib_Array.make(sz_1.contents + 1 | 0, /* [] */0)
 };
 
 let n_items = {
@@ -52,7 +52,7 @@ function hashVal(x, y, v) {
 function resize(newSize) {
   let arr = htab.contents;
   let newSz_1 = newSize - 1 | 0;
-  let newArr = Belt_Array.make(newSize, /* [] */0);
+  let newArr = Stdlib_Array.make(newSize, /* [] */0);
   let copyBucket = _bucket => {
     while (true) {
       let bucket = _bucket;
@@ -118,7 +118,7 @@ function insert(idl, idh, v, ind, bucket, newNode) {
 
 function resetUnique() {
   sz_1.contents = 8191;
-  htab.contents = Belt_Array.make(sz_1.contents + 1 | 0, /* [] */0);
+  htab.contents = Stdlib_Array.make(sz_1.contents + 1 | 0, /* [] */0);
   n_items.contents = 0;
   nodeC.contents = 1;
 }
@@ -193,21 +193,21 @@ function mkVar(x) {
   return mkNode("Zero", x, "One");
 }
 
-let andslot1 = Belt_Array.make(1999, 0);
+let andslot1 = Stdlib_Array.make(1999, 0);
 
-let andslot2 = Belt_Array.make(1999, 0);
+let andslot2 = Stdlib_Array.make(1999, 0);
 
-let andslot3 = Belt_Array.make(1999, "Zero");
+let andslot3 = Stdlib_Array.make(1999, "Zero");
 
-let xorslot1 = Belt_Array.make(1999, 0);
+let xorslot1 = Stdlib_Array.make(1999, 0);
 
-let xorslot2 = Belt_Array.make(1999, 0);
+let xorslot2 = Stdlib_Array.make(1999, 0);
 
-let xorslot3 = Belt_Array.make(1999, "Zero");
+let xorslot3 = Stdlib_Array.make(1999, "Zero");
 
-let notslot1 = Belt_Array.make(1999, 0);
+let notslot1 = Stdlib_Array.make(1999, 0);
 
-let notslot2 = Belt_Array.make(1999, "One");
+let notslot2 = Stdlib_Array.make(1999, "One");
 
 function hash(x, y) {
   return ((x << 1) + y | 0) % 1999;
@@ -352,7 +352,7 @@ function random() {
 }
 
 function random_vars(n) {
-  let vars = Belt_Array.make(n, false);
+  let vars = Stdlib_Array.make(n, false);
   for (let i = 0; i < n; ++i) {
     vars[i] = random();
   }
diff --git a/tests/tests/src/bdd.res b/tests/tests/src/bdd.res
index 32a89c26f67..3428026261d 100644
--- a/tests/tests/src/bdd.res
+++ b/tests/tests/src/bdd.res
@@ -39,14 +39,14 @@ let getId = bdd =>
 let initSize_1 = 8 * 1024 - 1
 let nodeC = ref(1)
 let sz_1 = ref(initSize_1)
-let htab = ref(Belt.Array.make(sz_1.contents + 1, list{}))
+let htab = ref(Array.make(~length=sz_1.contents + 1, list{}))
 let n_items = ref(0)
 let hashVal = (x, y, v) => lsl(x, 1) + y + lsl(v, 2)
 
 let resize = newSize => {
   let arr = htab.contents
   let newSz_1 = newSize - 1
-  let newArr = Belt.Array.make(newSize, list{})
+  let newArr = Array.make(~length=newSize, list{})
   let rec copyBucket = bucket =>
     switch bucket {
     | list{} => ()
@@ -81,7 +81,7 @@ let rec insert = (idl, idh, v, ind, bucket, newNode) =>
 
 let resetUnique = () => {
   sz_1 := initSize_1
-  htab := Belt.Array.make(sz_1.contents + 1, list{})
+  htab := Array.make(~length=sz_1.contents + 1, list{})
   n_items := 0
   nodeC := 1
 }
@@ -144,14 +144,14 @@ let mkVar = x => mkNode(zero, x, one)
 
 let cacheSize = 1999
 
-let andslot1 = Belt.Array.make(cacheSize, 0)
-let andslot2 = Belt.Array.make(cacheSize, 0)
-let andslot3 = Belt.Array.make(cacheSize, zero)
-let xorslot1 = Belt.Array.make(cacheSize, 0)
-let xorslot2 = Belt.Array.make(cacheSize, 0)
-let xorslot3 = Belt.Array.make(cacheSize, zero)
-let notslot1 = Belt.Array.make(cacheSize, 0)
-let notslot2 = Belt.Array.make(cacheSize, one)
+let andslot1 = Array.make(~length=cacheSize, 0)
+let andslot2 = Array.make(~length=cacheSize, 0)
+let andslot3 = Array.make(~length=cacheSize, zero)
+let xorslot1 = Array.make(~length=cacheSize, 0)
+let xorslot2 = Array.make(~length=cacheSize, 0)
+let xorslot3 = Array.make(~length=cacheSize, zero)
+let notslot1 = Array.make(~length=cacheSize, 0)
+let notslot2 = Array.make(~length=cacheSize, one)
 let hash = (x, y) => mod(lsl(x, 1) + y, cacheSize)
 
 let rec not = n =>
@@ -254,7 +254,7 @@ let random = () => {
 }
 
 let random_vars = n => {
-  let vars = Belt.Array.make(n, false)
+  let vars = Array.make(~length=n, false)
   for i in 0 to n - 1 {
     vars->Array.setUnsafe(i, random())
   }
@@ -274,7 +274,7 @@ let test_hwb = (bdd, vars) => {
         eval bdd vars = false if n = 0
      where n is the number of "true" elements in vars. */
   let ntrue = ref(0)
-  for i in 0 to Belt.Array.length(vars) - 1 {
+  for i in 0 to Array.length(vars) - 1 {
     if vars->Array.getUnsafe(i) {
       incr(ntrue)
     }
diff --git a/tests/tests/src/bench.mjs b/tests/tests/src/bench.mjs
index f86e79938d0..f48d7376714 100644
--- a/tests/tests/src/bench.mjs
+++ b/tests/tests/src/bench.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 function map(f, a) {
   let f$1 = x => f(x);
@@ -9,7 +9,7 @@ function map(f, a) {
   if (l === 0) {
     return [];
   }
-  let r = Belt_Array.make(l, f$1(a[0]));
+  let r = Stdlib_Array.make(l, f$1(a[0]));
   for (let i = 1; i < l; ++i) {
     r[i] = f$1(a[i]);
   }
@@ -24,7 +24,7 @@ function init(l, f) {
   if (l < 0) {
     return Pervasives.invalid_arg("Array.init");
   }
-  let res = Belt_Array.make(l, f$1(0));
+  let res = Stdlib_Array.make(l, f$1(0));
   for (let i = 1; i < l; ++i) {
     res[i] = f$1(i);
   }
diff --git a/tests/tests/src/bench.res b/tests/tests/src/bench.res
index 690c65de190..5e025249d3f 100644
--- a/tests/tests/src/bench.res
+++ b/tests/tests/src/bench.res
@@ -1,11 +1,9 @@
-open Belt
-
 let map = (f, a) => {
   let l = Array.length(a)
   if l == 0 {
     []
   } else {
-    let r = Array.make(l, f(Array.getUnsafe(a, 0)))
+    let r = Array.make(~length=l, f(Array.getUnsafe(a, 0)))
     for i in 1 to l - 1 {
       Array.setUnsafe(r, i, f(Array.getUnsafe(a, i)))
     }
@@ -24,7 +22,7 @@ let init = (l, f) =>
     /* See #6575. We could also check for maximum array size, but this depends
      on whether we create a float array or a regular one... */
 
-    let res = Array.make(l, f(0))
+    let res = Array.make(~length=l, f(0))
     for i in 1 to pred(l) {
       Array.setUnsafe(res, i, f(i))
     }
diff --git a/tests/tests/src/block_alias_test.mjs b/tests/tests/src/block_alias_test.mjs
index edb7b0b9856..0fcd2329302 100644
--- a/tests/tests/src/block_alias_test.mjs
+++ b/tests/tests/src/block_alias_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
 
 let Block = {};
@@ -38,7 +38,7 @@ let f = Primitive_object.equal;
 
 Mocha.describe("Block_alias_test", () => {
   Mocha.test("block_alias_tests", () => {
-    Test_utils.eq("File \"block_alias_test.res\", line 28, characters 7-14", Belt_List.length({
+    Test_utils.eq("File \"block_alias_test.res\", line 28, characters 7-14", Stdlib_List.length({
       hd: 1,
       tl: {
         hd: 2,
@@ -54,7 +54,7 @@ Mocha.describe("Block_alias_test", () => {
   });
 });
 
-let h = Belt_List.length;
+let h = Stdlib_List.length;
 
 export {
   Block,
diff --git a/tests/tests/src/block_alias_test.res b/tests/tests/src/block_alias_test.res
index df219eefd44..74885e253ca 100644
--- a/tests/tests/src/block_alias_test.res
+++ b/tests/tests/src/block_alias_test.res
@@ -20,11 +20,11 @@ module V = {
 }
 let f = (a, b) => a == b
 
-let h = Belt.List.length
+let h = List.length
 
 describe(__MODULE__, () => {
   test("block_alias_tests", () => {
-    let h = Belt.List.length
+    let h = List.length
     eq(__LOC__, h(list{1, 2}), 2)
     ok(__LOC__, f(v0, A(0, 1)))
     eq(__LOC__, v0, N.v1)
diff --git a/tests/tests/src/coercion_module_alias_test.mjs b/tests/tests/src/coercion_module_alias_test.mjs
index 4aa1ae841ee..5984f94a192 100644
--- a/tests/tests/src/coercion_module_alias_test.mjs
+++ b/tests/tests/src/coercion_module_alias_test.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Char from "@rescript/runtime/lib/es6/Char.mjs";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function l(prim) {
   console.log(prim);
@@ -17,10 +17,10 @@ let C3 = Char;
 
 console.log(66);
 
-let f = Belt_List.length;
+let f = Stdlib_List.length;
 
 function g(x) {
-  return Belt_List.length(Belt_List.map(x, prim => prim + 1 | 0));
+  return Stdlib_List.length(Stdlib_List.map(x, prim => prim + 1 | 0));
 }
 
 function F(X) {
diff --git a/tests/tests/src/coercion_module_alias_test.res b/tests/tests/src/coercion_module_alias_test.res
index 3801348a0d9..26d0970c3f7 100644
--- a/tests/tests/src/coercion_module_alias_test.res
+++ b/tests/tests/src/coercion_module_alias_test.res
@@ -1,5 +1,3 @@
-open Belt
-
 let l = Console.log
 module C = Char
 
diff --git a/tests/tests/src/cps_test.mjs b/tests/tests/src/cps_test.mjs
index 0f44629e98a..008e854db08 100644
--- a/tests/tests/src/cps_test.mjs
+++ b/tests/tests/src/cps_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 function test_sum() {
   let v = {
@@ -31,11 +31,11 @@ function test_closure() {
   let v = {
     contents: 0
   };
-  let arr = Belt_Array.make(6, x => x);
+  let arr = Stdlib_Array.make(6, x => x);
   for (let i = 0; i <= 5; ++i) {
     arr[i] = param => i;
   }
-  Belt_Array.forEach(arr, i => {
+  arr.forEach(i => {
     v.contents = v.contents + i(0) | 0;
   });
   return v.contents;
@@ -45,12 +45,12 @@ function test_closure2() {
   let v = {
     contents: 0
   };
-  let arr = Belt_Array.make(6, x => x);
+  let arr = Stdlib_Array.make(6, x => x);
   for (let i = 0; i <= 5; ++i) {
     let j = i + i | 0;
     arr[i] = param => j;
   }
-  Belt_Array.forEach(arr, i => {
+  arr.forEach(i => {
     v.contents = v.contents + i(0) | 0;
   });
   return v.contents;
diff --git a/tests/tests/src/cps_test.res b/tests/tests/src/cps_test.res
index a5e998733c0..e94233b2f50 100644
--- a/tests/tests/src/cps_test.res
+++ b/tests/tests/src/cps_test.res
@@ -19,23 +19,23 @@ let test_sum = () => {
 let test_closure = () => {
   let n = 6
   let v = ref(0)
-  let arr = Belt.Array.make(n, x => x)
+  let arr = Array.make(~length=n, x => x)
   for i in 0 to n - 1 {
     arr[i] = _ => i
   }
-  arr->Belt.Array.forEach(i => v := v.contents + i(0))
+  arr->Array.forEach(i => v := v.contents + i(0))
   v.contents
 }
 
 let test_closure2 = () => {
   let n = 6
   let v = ref(0)
-  let arr = Belt.Array.make(n, x => x)
+  let arr = Array.make(~length=n, x => x)
   for i in 0 to n - 1 {
     let j = i + i
     arr[i] = _ => j
   }
-  arr->Belt.Array.forEach(i => v := v.contents + i(0))
+  arr->Array.forEach(i => v := v.contents + i(0))
   v.contents
 }
 
diff --git a/tests/tests/src/directives.mjs b/tests/tests/src/directives.mjs
index 7814c1205e0..205ac9baa69 100644
--- a/tests/tests/src/directives.mjs
+++ b/tests/tests/src/directives.mjs
@@ -2,9 +2,10 @@ first directive;
 second directive;
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 
-let a = Belt_Array.forEach;
+function a(prim0, prim1) {
+  prim0.forEach(prim1);
+}
 
 export {
   a,
diff --git a/tests/tests/src/directives.res b/tests/tests/src/directives.res
index e6369d8ea99..a6907970277 100644
--- a/tests/tests/src/directives.res
+++ b/tests/tests/src/directives.res
@@ -1,4 +1,4 @@
 @@directive("first directive;")
 @@directive("second directive;")
 
-let a = Belt.Array.forEach
+let a = Array.forEach
diff --git a/tests/tests/src/earger_curry_test.mjs b/tests/tests/src/earger_curry_test.mjs
index 0ec6b670641..32b91816480 100644
--- a/tests/tests/src/earger_curry_test.mjs
+++ b/tests/tests/src/earger_curry_test.mjs
@@ -1,9 +1,9 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 function map(f, a) {
   let f$1 = x => f(x);
@@ -11,7 +11,7 @@ function map(f, a) {
   if (l === 0) {
     return [];
   }
-  let r = Belt_Array.make(l, f$1(a[0]));
+  let r = Stdlib_Array.make(l, f$1(a[0]));
   for (let i = 1; i < l; ++i) {
     r[i] = f$1(a[i]);
   }
@@ -26,7 +26,7 @@ function init(l, f) {
   if (l < 0) {
     return Pervasives.invalid_arg("Array.init");
   }
-  let res = Belt_Array.make(l, f$1(0));
+  let res = Stdlib_Array.make(l, f$1(0));
   for (let i = 1; i < l; ++i) {
     res[i] = f$1(i);
   }
@@ -43,10 +43,10 @@ function fold_left(f, x, a) {
 }
 
 function f2() {
-  let arr = Belt_Array.init(30000000, i => i);
-  let b = Belt_Array.map(arr, i => i + i - 1);
-  let v = Belt_Array.reduceReverse(b, 0, (prim0, prim1) => prim0 + prim1);
-  console.log(String(v));
+  let arr = init(30000000, i => i);
+  let b = arr.map(i => i + i - 1);
+  let v = Stdlib_Array.reduceRight(b, 0, (prim0, prim1) => prim0 + prim1);
+  console.log(v.toString());
 }
 
 f2();
@@ -96,11 +96,11 @@ let c = g(0)(3, 4);
 let d = g(0)(3, 5);
 
 Mocha.describe("Earger_curry_test", () => {
-  Mocha.test("earger curry a", () => Test_utils.eq("File \"earger_curry_test.res\", line 139, characters 34-41", a, 10));
-  Mocha.test("earger curry b", () => Test_utils.eq("File \"earger_curry_test.res\", line 140, characters 34-41", b, 11));
-  Mocha.test("earger curry c", () => Test_utils.eq("File \"earger_curry_test.res\", line 141, characters 34-41", c, 10));
-  Mocha.test("earger curry d", () => Test_utils.eq("File \"earger_curry_test.res\", line 142, characters 34-41", d, 11));
-  Mocha.test("earger curry all_v", () => Test_utils.eq("File \"earger_curry_test.res\", line 143, characters 38-45", all_v.contents, {
+  Mocha.test("earger curry a", () => Test_utils.eq("File \"earger_curry_test.res\", line 137, characters 34-41", a, 10));
+  Mocha.test("earger curry b", () => Test_utils.eq("File \"earger_curry_test.res\", line 138, characters 34-41", b, 11));
+  Mocha.test("earger curry c", () => Test_utils.eq("File \"earger_curry_test.res\", line 139, characters 34-41", c, 10));
+  Mocha.test("earger curry d", () => Test_utils.eq("File \"earger_curry_test.res\", line 140, characters 34-41", d, 11));
+  Mocha.test("earger curry all_v", () => Test_utils.eq("File \"earger_curry_test.res\", line 141, characters 38-45", all_v.contents, {
     hd: 8,
     tl: {
       hd: 6,
diff --git a/tests/tests/src/earger_curry_test.res b/tests/tests/src/earger_curry_test.res
index 310d08464fd..07cb32b549c 100644
--- a/tests/tests/src/earger_curry_test.res
+++ b/tests/tests/src/earger_curry_test.res
@@ -1,5 +1,3 @@
-open Belt
-
 let f = g => x => g(x)
 
 let map = (f, a) => {
@@ -7,7 +5,7 @@ let map = (f, a) => {
   if l == 0 {
     []
   } else {
-    let r = Array.make(l, f(Array.getUnsafe(a, 0)))
+    let r = Array.make(~length=l, f(Array.getUnsafe(a, 0)))
     for i in 1 to l - 1 {
       Array.setUnsafe(r, i, f(Array.getUnsafe(a, i)))
     }
@@ -26,7 +24,7 @@ let init = (l, f) =>
     /* See #6575. We could also check for maximum array size, but this depends
      on whether we create a float array or a regular one... */
 
-    let res = Array.make(l, f(0))
+    let res = Array.make(~length=l, f(0))
     for i in 1 to pred(l) {
       Array.setUnsafe(res, i, f(i))
     }
@@ -54,7 +52,7 @@ let f = {
   () => {
     let arr = init(10000000, i => float_of_int(i))
     let b = arr->map(i => i +. i -. 1.)
-    let v = b->reduceReverse(0., \"+.")
+    let v = b->Array.reduceRight(0., \"+.")
     v->Float.toString->Console.log
   }
 }
@@ -63,7 +61,7 @@ let f2 = () => {
   open Array
   let arr = init(30_000_000, i => float_of_int(i))
   let b = arr->map(i => i +. i -. 1.)
-  let v = b->reduceReverse(0., \"+.")
+  let v = b->Array.reduceRight(0., \"+.")
   v->Float.toString->Console.log
 }
 
diff --git a/tests/tests/src/event_ffi.mjs b/tests/tests/src/event_ffi.mjs
index 15f7d8da753..288a05575bc 100644
--- a/tests/tests/src/event_ffi.mjs
+++ b/tests/tests/src/event_ffi.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function h0(x) {
   return x();
@@ -56,7 +56,7 @@ function xx() {
   };
 }
 
-let test_as = Belt_List.map;
+let test_as = Stdlib_List.map;
 
 export {
   h0,
diff --git a/tests/tests/src/event_ffi.res b/tests/tests/src/event_ffi.res
index 83c0a4b33c0..57b3da34553 100644
--- a/tests/tests/src/event_ffi.res
+++ b/tests/tests/src/event_ffi.res
@@ -22,7 +22,7 @@ let a2 = (x, y) => x + y
 let a3 = (x, y, z) => x + y + z
 /* polymoprhic restriction */
 
-let test_as: (_ as 'b, 'a => 'a) => 'b = Belt.List.map
+let test_as: (_ as 'b, 'a => 'a) => 'b = List.map
 
 let xx: unit => _ => unit = () => _ => Console.log(3)
 
diff --git a/tests/tests/src/exception_alias.mjs b/tests/tests/src/exception_alias.mjs
index bd3ce69ff67..c057d5d3926 100644
--- a/tests/tests/src/exception_alias.mjs
+++ b/tests/tests/src/exception_alias.mjs
@@ -1,12 +1,12 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 let a0 = {
   RE_EXN_ID: "Not_found"
 };
 
-let b = Belt_List.length({
+let b = Stdlib_List.length({
   hd: 1,
   tl: {
     hd: 2,
@@ -15,96 +15,65 @@ let b = Belt_List.length({
 });
 
 let List = {
-  size: Belt_List.size,
-  head: Belt_List.head,
-  headExn: Belt_List.headExn,
-  headOrThrow: Belt_List.headOrThrow,
-  tail: Belt_List.tail,
-  tailExn: Belt_List.tailExn,
-  tailOrThrow: Belt_List.tailOrThrow,
-  add: Belt_List.add,
-  get: Belt_List.get,
-  getExn: Belt_List.getExn,
-  getOrThrow: Belt_List.getOrThrow,
-  make: Belt_List.make,
-  makeByU: Belt_List.makeByU,
-  makeBy: Belt_List.makeBy,
-  shuffle: Belt_List.shuffle,
-  drop: Belt_List.drop,
-  take: Belt_List.take,
-  splitAt: Belt_List.splitAt,
-  concat: Belt_List.concat,
-  concatMany: Belt_List.concatMany,
-  reverseConcat: Belt_List.reverseConcat,
-  flatten: Belt_List.flatten,
-  mapU: Belt_List.mapU,
-  map: Belt_List.map,
-  zip: Belt_List.zip,
-  zipByU: Belt_List.zipByU,
-  zipBy: Belt_List.zipBy,
-  mapWithIndexU: Belt_List.mapWithIndexU,
-  mapWithIndex: Belt_List.mapWithIndex,
-  fromArray: Belt_List.fromArray,
-  toArray: Belt_List.toArray,
-  reverse: Belt_List.reverse,
-  mapReverseU: Belt_List.mapReverseU,
-  mapReverse: Belt_List.mapReverse,
-  forEachU: Belt_List.forEachU,
-  forEach: Belt_List.forEach,
-  forEachWithIndexU: Belt_List.forEachWithIndexU,
-  forEachWithIndex: Belt_List.forEachWithIndex,
-  reduceU: Belt_List.reduceU,
-  reduce: Belt_List.reduce,
-  reduceWithIndexU: Belt_List.reduceWithIndexU,
-  reduceWithIndex: Belt_List.reduceWithIndex,
-  reduceReverseU: Belt_List.reduceReverseU,
-  reduceReverse: Belt_List.reduceReverse,
-  mapReverse2U: Belt_List.mapReverse2U,
-  mapReverse2: Belt_List.mapReverse2,
-  forEach2U: Belt_List.forEach2U,
-  forEach2: Belt_List.forEach2,
-  reduce2U: Belt_List.reduce2U,
-  reduce2: Belt_List.reduce2,
-  reduceReverse2U: Belt_List.reduceReverse2U,
-  reduceReverse2: Belt_List.reduceReverse2,
-  everyU: Belt_List.everyU,
-  every: Belt_List.every,
-  someU: Belt_List.someU,
-  some: Belt_List.some,
-  every2U: Belt_List.every2U,
-  every2: Belt_List.every2,
-  some2U: Belt_List.some2U,
-  some2: Belt_List.some2,
-  cmpByLength: Belt_List.cmpByLength,
-  cmpU: Belt_List.cmpU,
-  cmp: Belt_List.cmp,
-  eqU: Belt_List.eqU,
-  eq: Belt_List.eq,
-  hasU: Belt_List.hasU,
-  has: Belt_List.has,
-  getByU: Belt_List.getByU,
-  getBy: Belt_List.getBy,
-  keepU: Belt_List.keepU,
-  keep: Belt_List.keep,
-  filter: Belt_List.filter,
-  keepWithIndexU: Belt_List.keepWithIndexU,
-  keepWithIndex: Belt_List.keepWithIndex,
-  filterWithIndex: Belt_List.filterWithIndex,
-  keepMapU: Belt_List.keepMapU,
-  keepMap: Belt_List.keepMap,
-  partitionU: Belt_List.partitionU,
-  partition: Belt_List.partition,
-  unzip: Belt_List.unzip,
-  getAssocU: Belt_List.getAssocU,
-  getAssoc: Belt_List.getAssoc,
-  hasAssocU: Belt_List.hasAssocU,
-  hasAssoc: Belt_List.hasAssoc,
-  removeAssocU: Belt_List.removeAssocU,
-  removeAssoc: Belt_List.removeAssoc,
-  setAssocU: Belt_List.setAssocU,
-  setAssoc: Belt_List.setAssoc,
-  sortU: Belt_List.sortU,
-  sort: Belt_List.sort,
+  size: Stdlib_List.size,
+  head: Stdlib_List.head,
+  headExn: Stdlib_List.headExn,
+  headOrThrow: Stdlib_List.headOrThrow,
+  tail: Stdlib_List.tail,
+  tailExn: Stdlib_List.tailExn,
+  tailOrThrow: Stdlib_List.tailOrThrow,
+  add: Stdlib_List.add,
+  get: Stdlib_List.get,
+  getExn: Stdlib_List.getExn,
+  getOrThrow: Stdlib_List.getOrThrow,
+  make: Stdlib_List.make,
+  fromInitializer: Stdlib_List.fromInitializer,
+  shuffle: Stdlib_List.shuffle,
+  toShuffled: Stdlib_List.toShuffled,
+  drop: Stdlib_List.drop,
+  take: Stdlib_List.take,
+  splitAt: Stdlib_List.splitAt,
+  concat: Stdlib_List.concat,
+  concatMany: Stdlib_List.concatMany,
+  reverseConcat: Stdlib_List.reverseConcat,
+  flat: Stdlib_List.flat,
+  map: Stdlib_List.map,
+  zip: Stdlib_List.zip,
+  zipBy: Stdlib_List.zipBy,
+  mapWithIndex: Stdlib_List.mapWithIndex,
+  fromArray: Stdlib_List.fromArray,
+  toArray: Stdlib_List.toArray,
+  reverse: Stdlib_List.reverse,
+  mapReverse: Stdlib_List.mapReverse,
+  forEach: Stdlib_List.forEach,
+  forEachWithIndex: Stdlib_List.forEachWithIndex,
+  reduce: Stdlib_List.reduce,
+  reduceWithIndex: Stdlib_List.reduceWithIndex,
+  reduceReverse: Stdlib_List.reduceReverse,
+  mapReverse2: Stdlib_List.mapReverse2,
+  forEach2: Stdlib_List.forEach2,
+  reduce2: Stdlib_List.reduce2,
+  reduceReverse2: Stdlib_List.reduceReverse2,
+  every: Stdlib_List.every,
+  some: Stdlib_List.some,
+  every2: Stdlib_List.every2,
+  some2: Stdlib_List.some2,
+  compareLength: Stdlib_List.compareLength,
+  compare: Stdlib_List.compare,
+  equal: Stdlib_List.equal,
+  has: Stdlib_List.has,
+  includes: Stdlib_List.includes,
+  find: Stdlib_List.find,
+  filter: Stdlib_List.filter,
+  filterWithIndex: Stdlib_List.filterWithIndex,
+  filterMap: Stdlib_List.filterMap,
+  partition: Stdlib_List.partition,
+  unzip: Stdlib_List.unzip,
+  getAssoc: Stdlib_List.getAssoc,
+  hasAssoc: Stdlib_List.hasAssoc,
+  removeAssoc: Stdlib_List.removeAssoc,
+  setAssoc: Stdlib_List.setAssoc,
+  sort: Stdlib_List.sort,
   b: b,
   length: 3
 };
diff --git a/tests/tests/src/exception_alias.res b/tests/tests/src/exception_alias.res
index 205b2c1d781..cdd03d51900 100644
--- a/tests/tests/src/exception_alias.res
+++ b/tests/tests/src/exception_alias.res
@@ -10,8 +10,6 @@ let a4 = a3
 
 let a5 = a4
 
-open Belt
-
 module List = {
   include List
   let b = length(list{1, 2})
diff --git a/tests/tests/src/exception_raise_test.mjs b/tests/tests/src/exception_raise_test.mjs
index c26ef72c659..016b263105b 100644
--- a/tests/tests/src/exception_raise_test.mjs
+++ b/tests/tests/src/exception_raise_test.mjs
@@ -1,9 +1,9 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Stdlib_Exn from "@rescript/runtime/lib/es6/Stdlib_Exn.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_exceptions from "@rescript/runtime/lib/es6/Primitive_exceptions.mjs";
 
 let Local = /* @__PURE__ */Primitive_exceptions.create("Exception_raise_test.Local");
@@ -138,7 +138,7 @@ function input_lines(ic, _acc) {
     try {
       line = input_line(ic);
     } catch (exn) {
-      return Belt_List.reverse(acc);
+      return Stdlib_List.reverse(acc);
     }
     _acc = {
       hd: line,
diff --git a/tests/tests/src/exception_raise_test.res b/tests/tests/src/exception_raise_test.res
index 5d44a46936e..ca6ea90f722 100644
--- a/tests/tests/src/exception_raise_test.res
+++ b/tests/tests/src/exception_raise_test.res
@@ -63,7 +63,7 @@ type in_channel
 @val external input_line: in_channel => string = "input_line"
 let rec input_lines = (ic, acc) =>
   switch input_line(ic) {
-  | exception _ => Belt.List.reverse(acc)
+  | exception _ => List.reverse(acc)
   | line => input_lines(ic, list{line, ...acc})
   }
 
diff --git a/tests/tests/src/ext_array_test.mjs b/tests/tests/src/ext_array_test.mjs
index 0cbb2cdbe24..8c52d21947f 100644
--- a/tests/tests/src/ext_array_test.mjs
+++ b/tests/tests/src/ext_array_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 function reverse_range(a, i, len) {
@@ -25,7 +25,7 @@ function reverse(a) {
   if (b_len === 0) {
     return [];
   }
-  let b = a.slice(0);
+  let b = a.slice();
   for (let i = 0; i < b_len; ++i) {
     b[i] = a[(b_len - 1 | 0) - i | 0];
   }
@@ -36,8 +36,8 @@ function reverse_of_list(x) {
   if (x === 0) {
     return [];
   }
-  let len = Belt_List.length(x);
-  let a = Belt_Array.make(len, x.hd);
+  let len = Stdlib_List.length(x);
+  let a = Stdlib_Array.make(len, x.hd);
   let _i = 0;
   let _x = x.tl;
   while (true) {
@@ -106,7 +106,7 @@ function range(from, to_) {
   if (from > to_) {
     return Pervasives.invalid_arg("Ext_array_test.range");
   } else {
-    return Belt_Array.init((to_ - from | 0) + 1 | 0, i => i + from | 0);
+    return Stdlib_Array.fromInitializer((to_ - from | 0) + 1 | 0, i => i + from | 0);
   }
 }
 
@@ -115,7 +115,7 @@ function map2i(f, a, b) {
   if (len !== b.length) {
     return Pervasives.invalid_arg("Ext_array_test.map2i");
   } else {
-    return Belt_Array.mapWithIndex(a, (i, a) => f(i, a, b[i]));
+    return a.map((i, a) => f(i, a, b[i]));
   }
 }
 
@@ -151,8 +151,8 @@ function of_list_map(f, a) {
   }
   let tl = a.tl;
   let hd = f(a.hd);
-  let len = Belt_List.length(tl) + 1 | 0;
-  let arr = Belt_Array.make(len, hd);
+  let len = Stdlib_List.length(tl) + 1 | 0;
+  let arr = Stdlib_Array.make(len, hd);
   let _i = 1;
   let _x = tl;
   while (true) {
@@ -192,8 +192,8 @@ function rfind_and_split(arr, cmp, v) {
     return {
       NAME: "Split",
       VAL: [
-        Belt_Array.slice(arr, 0, i),
-        Belt_Array.slice(arr, i + 1 | 0, (arr.length - i | 0) - 1 | 0)
+        arr.slice(0, i),
+        arr.slice(i + 1 | 0)
       ]
     };
   }
@@ -223,8 +223,8 @@ function find_and_split(arr, cmp, v) {
     return {
       NAME: "Split",
       VAL: [
-        Belt_Array.slice(arr, 0, i),
-        Belt_Array.slice(arr, i + 1 | 0, (arr.length - i | 0) - 1 | 0)
+        arr.slice(0, i),
+        arr.slice(i + 1 | 0)
       ]
     };
   }
diff --git a/tests/tests/src/ext_array_test.res b/tests/tests/src/ext_array_test.res
index c2fbe5e4f93..4bf4b373e8b 100644
--- a/tests/tests/src/ext_array_test.res
+++ b/tests/tests/src/ext_array_test.res
@@ -22,8 +22,6 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
 
-open Belt
-
 let reverse_range = (a, i, len) =>
   if len == 0 {
     ()
@@ -55,7 +53,7 @@ let reverse_of_list = x =>
   | list{} => []
   | list{hd, ...tl} as l =>
     let len = List.length(l)
-    let a = Array.make(len, hd)
+    let a = Array.make(~length=len, hd)
     let rec fill = (i, x) =>
       switch x {
       | list{} => a
@@ -101,7 +99,7 @@ let range = (from, to_) =>
   if from > to_ {
     invalid_arg("Ext_array_test.range")
   } else {
-    Array.init(to_ - from + 1, i => i + from)
+    Array.fromInitializer(~length=to_ - from + 1, i => i + from)
   }
 
 let map2i = (f, a, b) => {
@@ -140,7 +138,7 @@ let of_list_map = (f, a) =>
   | list{h, ...tl} =>
     let hd = f(h)
     let len = List.length(tl) + 1
-    let arr = Array.make(len, hd)
+    let arr = Array.make(~length=len, hd)
     let rec fill = (i, x) =>
       switch x {
       | list{} => arr
@@ -182,10 +180,7 @@ let rfind_and_split = (arr, cmp, v): split<_> => {
   if i < 0 {
     #No_split
   } else {
-    #Split(
-      Array.slice(arr, ~offset=0, ~len=i),
-      Array.slice(arr, ~offset=i + 1, ~len=Array.length(arr) - i - 1),
-    )
+    #Split(Array.slice(arr, ~start=0, ~end=i), Array.slice(arr, ~start=i + 1))
   }
 }
 
@@ -207,10 +202,7 @@ let find_and_split = (arr, cmp, v): split<_> => {
   if i < 0 {
     #No_split
   } else {
-    #Split(
-      Array.slice(arr, ~offset=0, ~len=i),
-      Array.slice(arr, ~offset=i + 1, ~len=Array.length(arr) - i - 1),
-    )
+    #Split(Array.slice(arr, ~start=0, ~end=i), Array.slice(arr, ~start=i + 1))
   }
 }
 
diff --git a/tests/tests/src/flexible_array_test.mjs b/tests/tests/src/flexible_array_test.mjs
index a2e3e8b4aef..10c14996b35 100644
--- a/tests/tests/src/flexible_array_test.mjs
+++ b/tests/tests/src/flexible_array_test.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
 
 function sub(_tr, _k) {
@@ -307,9 +307,9 @@ if (!$eq$tilde(sort(u), [
   };
 }
 
-let v = Belt_Array.init(500, i => 500 - i | 0);
+let v = Stdlib_Array.fromInitializer(500, i => 500 - i | 0);
 
-$eq$tilde(sort(of_array(v)), Belt_Array.init(500, i => i + 1 | 0));
+$eq$tilde(sort(of_array(v)), Stdlib_Array.fromInitializer(500, i => i + 1 | 0));
 
 export {
   sub,
diff --git a/tests/tests/src/flexible_array_test.res b/tests/tests/src/flexible_array_test.res
index 87360e61607..17fc07b69cb 100644
--- a/tests/tests/src/flexible_array_test.res
+++ b/tests/tests/src/flexible_array_test.res
@@ -168,7 +168,7 @@ module Int_array: {
   }
   let of_array = arr => {
     let v = ref(empty)
-    for i in 0 to Belt.Array.length(arr) - 1 {
+    for i in 0 to Array.length(arr) - 1 {
       v := push_back(v.contents, arr->Array.getUnsafe(i))
     }
     v.contents
@@ -183,6 +183,6 @@ let _ = {
   let u = Int_array.of_array([1, 2, 2, 5, 3, 6])
   assert(\"=~"(Int_array.sort(u), [1, 2, 2, 3, 5, 6]))
   let len = 500
-  let v = Belt.Array.init(len, i => len - i)
-  \"=~"(Int_array.sort(Int_array.of_array(v)), Belt.Array.init(len, i => i + 1))
+  let v = Array.fromInitializer(~length=len, i => len - i)
+  \"=~"(Int_array.sort(Int_array.of_array(v)), Array.fromInitializer(~length=len, i => i + 1))
 }
diff --git a/tests/tests/src/for_loop_test.mjs b/tests/tests/src/for_loop_test.mjs
index 87d241555aa..9cd4c63ad46 100644
--- a/tests/tests/src/for_loop_test.mjs
+++ b/tests/tests/src/for_loop_test.mjs
@@ -1,9 +1,9 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 Mocha.describe("For_loop_test", () => {
   Mocha.test("for_loop_test_3", () => {
@@ -11,24 +11,24 @@ Mocha.describe("For_loop_test", () => {
       let v = {
         contents: 0
       };
-      let arr = Belt_Array.map(x, param => (() => {}));
+      let arr = x.map(param => (() => {}));
       for (let i = 0, i_finish = x.length; i < i_finish; ++i) {
         let j = (i << 1);
         arr[i] = () => {
           v.contents = v.contents + j | 0;
         };
       }
-      Belt_Array.forEach(arr, x => x());
+      arr.forEach(x => x());
       return v.contents;
     };
-    Test_utils.eq("File \"for_loop_test.res\", line 16, characters 7-14", 90, for_3(Belt_Array.make(10, 2)));
+    Test_utils.eq("File \"for_loop_test.res\", line 16, characters 7-14", 90, for_3(Stdlib_Array.make(10, 2)));
   });
   Mocha.test("for_loop_test_4", () => {
     let for_4 = x => {
       let v = {
         contents: 0
       };
-      let arr = Belt_Array.map(x, param => (() => {}));
+      let arr = x.map(param => (() => {}));
       for (let i = 0, i_finish = x.length; i < i_finish; ++i) {
         let j = (i << 1);
         let k = (j << 1);
@@ -36,34 +36,34 @@ Mocha.describe("For_loop_test", () => {
           v.contents = v.contents + k | 0;
         };
       }
-      Belt_Array.forEach(arr, x => x());
+      arr.forEach(x => x());
       return v.contents;
     };
-    Test_utils.eq("File \"for_loop_test.res\", line 31, characters 7-14", 180, for_4(Belt_Array.make(10, 2)));
+    Test_utils.eq("File \"for_loop_test.res\", line 31, characters 7-14", 180, for_4(Stdlib_Array.make(10, 2)));
   });
   Mocha.test("for_loop_test_5", () => {
     let for_5 = (x, u) => {
       let v = {
         contents: 0
       };
-      let arr = Belt_Array.map(x, param => (() => {}));
+      let arr = x.map(param => (() => {}));
       for (let i = 0, i_finish = x.length; i < i_finish; ++i) {
         let k = (u << 1) * u | 0;
         arr[i] = () => {
           v.contents = v.contents + k | 0;
         };
       }
-      Belt_Array.forEach(arr, x => x());
+      arr.forEach(x => x());
       return v.contents;
     };
-    Test_utils.eq("File \"for_loop_test.res\", line 46, characters 7-14", 2420, for_5(Belt_Array.make(10, 2), 11));
+    Test_utils.eq("File \"for_loop_test.res\", line 46, characters 7-14", 2420, for_5(Stdlib_Array.make(10, 2), 11));
   });
   Mocha.test("for_loop_test_6", () => {
     let for_6 = (x, u) => {
       let v = {
         contents: 0
       };
-      let arr = Belt_Array.map(x, param => (() => {}));
+      let arr = x.map(param => (() => {}));
       let v4 = {
         contents: 0
       };
@@ -87,7 +87,7 @@ Mocha.describe("For_loop_test", () => {
         }
         inspect_3 = v2.contents;
       }
-      Belt_Array.forEach(arr, x => x());
+      arr.forEach(x => x());
       return [
         v.contents,
         v4.contents,
@@ -100,14 +100,14 @@ Mocha.describe("For_loop_test", () => {
       1,
       2,
       3
-    ], for_6(Belt_Array.make(3, 0), 0));
+    ], for_6(Stdlib_Array.make(3, 0), 0));
   });
   Mocha.test("for_loop_test_7", () => {
     let for_7 = () => {
       let v = {
         contents: 0
       };
-      let arr = Belt_Array.make(21, () => {});
+      let arr = Stdlib_Array.make(21, () => {});
       for (let i = 0; i <= 6; ++i) {
         for (let j = 0; j <= 2; ++j) {
           arr[(i * 3 | 0) + j | 0] = () => {
@@ -115,7 +115,7 @@ Mocha.describe("For_loop_test", () => {
           };
         }
       }
-      Belt_Array.forEach(arr, f => f());
+      arr.forEach(f => f());
       return v.contents;
     };
     Test_utils.eq("File \"for_loop_test.res\", line 91, characters 7-14", 84, for_7());
@@ -125,7 +125,7 @@ Mocha.describe("For_loop_test", () => {
       let v = {
         contents: 0
       };
-      let arr = Belt_Array.make(21, () => {});
+      let arr = Stdlib_Array.make(21, () => {});
       for (let i = 0; i <= 6; ++i) {
         let k = (i << 1);
         for (let j = 0; j <= 2; ++j) {
@@ -135,7 +135,7 @@ Mocha.describe("For_loop_test", () => {
           };
         }
       }
-      Belt_Array.forEach(arr, f => f());
+      arr.forEach(f => f());
       return v.contents;
     };
     Test_utils.eq("File \"for_loop_test.res\", line 110, characters 7-14", 294, for_8());
@@ -157,8 +157,8 @@ Mocha.describe("For_loop_test", () => {
       let vv2 = {
         contents: 0
       };
-      let arr = Belt_Array.make(4, () => {});
-      let arr2 = Belt_Array.make(2, () => {});
+      let arr = Stdlib_Array.make(4, () => {});
+      let arr2 = Stdlib_Array.make(2, () => {});
       for (let i = 0; i <= 1; ++i) {
         let v$1 = {
           contents: 0
@@ -175,11 +175,11 @@ Mocha.describe("For_loop_test", () => {
           vv2.contents = vv2.contents + v$1.contents | 0;
         };
       }
-      Belt_Array.forEach(arr, f => f());
-      Belt_Array.forEach(arr2, f => f());
+      arr.forEach(f => f());
+      arr2.forEach(f => f());
       return [[
           vv.contents,
-          Belt_List.toArray(Belt_List.reverse(v.contents)),
+          Stdlib_List.toArray(Stdlib_List.reverse(v.contents)),
           vv2.contents
         ]];
     };
diff --git a/tests/tests/src/for_loop_test.res b/tests/tests/src/for_loop_test.res
index 9c1e9726aca..429ff44159e 100644
--- a/tests/tests/src/for_loop_test.res
+++ b/tests/tests/src/for_loop_test.res
@@ -5,51 +5,51 @@ describe(__MODULE__, () => {
   test("for_loop_test_3", () => {
     let for_3 = x => {
       let v = ref(0)
-      let arr = x->Belt.Array.map(_ => _ => ())
-      for i in 0 to Belt.Array.length(x) - 1 {
+      let arr = x->Array.map(_ => _ => ())
+      for i in 0 to Array.length(x) - 1 {
         let j = i * 2
         arr[i] = _ => v := v.contents + j
       }
-      arr->Belt.Array.forEach(x => x())
+      arr->Array.forEach(x => x())
       v.contents
     }
-    eq(__LOC__, 90, for_3(Belt.Array.make(10, 2)))
+    eq(__LOC__, 90, for_3(Array.make(~length=10, 2)))
   })
 
   test("for_loop_test_4", () => {
     let for_4 = x => {
       let v = ref(0)
-      let arr = x->Belt.Array.map(_ => _ => ())
-      for i in 0 to Belt.Array.length(x) - 1 {
+      let arr = x->Array.map(_ => _ => ())
+      for i in 0 to Array.length(x) - 1 {
         let j = i * 2
         let k = 2 * j
         arr[i] = _ => v := v.contents + k
       }
-      arr->Belt.Array.forEach(x => x())
+      arr->Array.forEach(x => x())
       v.contents
     }
-    eq(__LOC__, 180, for_4(Belt.Array.make(10, 2)))
+    eq(__LOC__, 180, for_4(Array.make(~length=10, 2)))
   })
 
   test("for_loop_test_5", () => {
     let for_5 = (x, u) => {
       let v = ref(0)
-      let arr = x->Belt.Array.map(_ => _ => ())
-      for i in 0 to Belt.Array.length(x) - 1 {
+      let arr = x->Array.map(_ => _ => ())
+      for i in 0 to Array.length(x) - 1 {
         let _j = i * 2
         let k = 2 * u * u
         arr[i] = _ => v := v.contents + k
       }
-      arr->Belt.Array.forEach(x => x())
+      arr->Array.forEach(x => x())
       v.contents
     }
-    eq(__LOC__, 2420, for_5(Belt.Array.make(10, 2), 11))
+    eq(__LOC__, 2420, for_5(Array.make(~length=10, 2), 11))
   })
 
   test("for_loop_test_6", () => {
     let for_6 = (x, u) => {
       let v = ref(0)
-      let arr = x->Belt.Array.map(_ => _ => ())
+      let arr = x->Array.map(_ => _ => ())
       let v4 = ref(0)
       let v5 = ref(0)
       let inspect_3 = ref(-1)
@@ -58,7 +58,7 @@ describe(__MODULE__, () => {
         incr(v5)
         let v2 = ref(0)
         let v3 = u
-        for i in 0 to Belt.Array.length(x) - 1 {
+        for i in 0 to Array.length(x) - 1 {
           let _j = i * 2
           let k = 2 * u * u
           let h = 2 * v5.contents
@@ -68,10 +68,10 @@ describe(__MODULE__, () => {
         }
         inspect_3 := v2.contents
       }
-      arr->Belt.Array.forEach(x => x())
+      arr->Array.forEach(x => x())
       [v.contents, v4.contents, v5.contents, inspect_3.contents]
     }
-    eq(__LOC__, [30, 1, 2, 3], for_6(Belt.Array.make(3, 0), 0))
+    eq(__LOC__, [30, 1, 2, 3], for_6(Array.make(~length=3, 0), 0))
   })
 
   test("for_loop_test_7", () => {
@@ -79,13 +79,13 @@ describe(__MODULE__, () => {
       let i_len = 7
       let j_len = 3
       let v = ref(0)
-      let arr = Belt.Array.make(i_len * j_len, _ => ())
+      let arr = Array.make(~length=i_len * j_len, _ => ())
       for i in 0 to i_len - 1 {
         for j in 0 to j_len - 1 {
           arr[i * j_len + j] = _ => v := v.contents + i + j
         }
       }
-      arr->Belt.Array.forEach(f => f())
+      arr->Array.forEach(f => f())
       v.contents
     }
     eq(__LOC__, 84, for_7())
@@ -96,7 +96,7 @@ describe(__MODULE__, () => {
       let i_len = 7
       let j_len = 3
       let v = ref(0)
-      let arr = Belt.Array.make(i_len * j_len, _ => ())
+      let arr = Array.make(~length=i_len * j_len, _ => ())
       for i in 0 to i_len - 1 {
         let k = 2 * i
         for j in 0 to j_len - 1 {
@@ -104,7 +104,7 @@ describe(__MODULE__, () => {
           arr[i * j_len + j] = _ => v := v.contents + i + j + h + k
         }
       }
-      arr->Belt.Array.forEach(f => f())
+      arr->Array.forEach(f => f())
       v.contents
     }
     eq(__LOC__, 294, for_8())
@@ -114,15 +114,15 @@ describe(__MODULE__, () => {
     let for_9 = () => {
       let (collect, get) = {
         let v: ref<list<int>> = ref(list{})
-        (x => v := list{x, ...v.contents}, () => Belt.List.toArray(Belt.List.reverse(v.contents)))
+        (x => v := list{x, ...v.contents}, () => List.toArray(List.reverse(v.contents)))
       }
 
       let i_len = 2
       let j_len = 2
       let vv = ref(0)
       let vv2 = ref(0)
-      let arr = Belt.Array.make(i_len * j_len, _ => ())
-      let arr2 = Belt.Array.make(i_len, _ => ())
+      let arr = Array.make(~length=i_len * j_len, _ => ())
+      let arr2 = Array.make(~length=i_len, _ => ())
       for i in 0 to i_len - 1 {
         let v = ref(0)
         /* incr v ; */
@@ -151,8 +151,8 @@ describe(__MODULE__, () => {
             v is changed
  */
       }
-      arr->Belt.Array.forEach(f => f())
-      arr2->Belt.Array.forEach(f => f())
+      arr->Array.forEach(f => f())
+      arr2->Array.forEach(f => f())
       [(vv.contents, get(), vv2.contents)]
     }
     eq(__LOC__, [(10, [1, 2, 2, 3], 5)], for_9())
diff --git a/tests/tests/src/global_module_alias_test.mjs b/tests/tests/src/global_module_alias_test.mjs
index 14646443b1e..ae9c72b4c24 100644
--- a/tests/tests/src/global_module_alias_test.mjs
+++ b/tests/tests/src/global_module_alias_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 let v = {
   contents: 0
@@ -22,11 +22,11 @@ function f() {
   v.contents = v.contents + 1 | 0;
   v.contents = v.contents + 1 | 0;
   v.contents = v.contents + 1 | 0;
-  return Belt_List;
+  return Stdlib_List;
 }
 
 function g() {
-  return Belt_List.length({
+  return Stdlib_List.length({
     hd: 1,
     tl: {
       hd: 2,
@@ -45,11 +45,11 @@ function xx() {
   v.contents = v.contents + 1 | 0;
   v.contents = v.contents + 1 | 0;
   v.contents = v.contents + 1 | 0;
-  return Belt_List;
+  return Stdlib_List;
 }
 
 Mocha.describe("Global_module_alias_test", () => {
-  Mocha.test("module alias basic operations", () => Test_utils.eq("File \"global_module_alias_test.res\", line 72, characters 7-14", Belt_List.length({
+  Mocha.test("module alias basic operations", () => Test_utils.eq("File \"global_module_alias_test.res\", line 71, characters 7-14", Stdlib_List.length({
     hd: 1,
     tl: {
       hd: 2,
@@ -69,12 +69,12 @@ Mocha.describe("Global_module_alias_test", () => {
     v.contents = v.contents + 1 | 0;
     v.contents = v.contents + 1 | 0;
     v.contents = v.contents + 1 | 0;
-    Test_utils.eq("File \"global_module_alias_test.res\", line 77, characters 7-14", v.contents, 12);
+    Test_utils.eq("File \"global_module_alias_test.res\", line 76, characters 7-14", v.contents, 12);
   });
-  Mocha.test("module alias unpacking", () => Test_utils.eq("File \"global_module_alias_test.res\", line 81, characters 7-14", g(), 4));
+  Mocha.test("module alias unpacking", () => Test_utils.eq("File \"global_module_alias_test.res\", line 80, characters 7-14", g(), 4));
   Mocha.test("module alias with functor applications", () => {
     let V = xx();
-    Test_utils.eq("File \"global_module_alias_test.res\", line 86, characters 7-14", V.length({
+    Test_utils.eq("File \"global_module_alias_test.res\", line 85, characters 7-14", V.length({
       hd: 1,
       tl: {
         hd: 2,
@@ -84,16 +84,16 @@ Mocha.describe("Global_module_alias_test", () => {
         }
       }
     }), 3);
-    Test_utils.eq("File \"global_module_alias_test.res\", line 87, characters 7-14", v.contents, 15);
+    Test_utils.eq("File \"global_module_alias_test.res\", line 86, characters 7-14", v.contents, 15);
     let H = f();
-    Test_utils.eq("File \"global_module_alias_test.res\", line 89, characters 7-14", H.length({
+    Test_utils.eq("File \"global_module_alias_test.res\", line 88, characters 7-14", H.length({
       hd: 1,
       tl: {
         hd: 2,
         tl: /* [] */0
       }
     }), 2);
-    Test_utils.eq("File \"global_module_alias_test.res\", line 90, characters 7-14", v.contents, 21);
+    Test_utils.eq("File \"global_module_alias_test.res\", line 89, characters 7-14", v.contents, 21);
   });
 });
 
diff --git a/tests/tests/src/global_module_alias_test.res b/tests/tests/src/global_module_alias_test.res
index 5e7c42eadfc..aecede20a3d 100644
--- a/tests/tests/src/global_module_alias_test.res
+++ b/tests/tests/src/global_module_alias_test.res
@@ -1,4 +1,3 @@
-open Belt
 open Mocha
 open Test_utils
 
diff --git a/tests/tests/src/gpr_1409_test.mjs b/tests/tests/src/gpr_1409_test.mjs
index c91dfb9a4bd..33dc60ce467 100644
--- a/tests/tests/src/gpr_1409_test.mjs
+++ b/tests/tests/src/gpr_1409_test.mjs
@@ -1,9 +1,9 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as String_set from "./string_set.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 let a = {};
@@ -20,7 +20,7 @@ function map(f, x) {
 
 function make(foo, param) {
   let tmp = {};
-  let tmp$1 = map(prim => String(prim), foo);
+  let tmp$1 = map(x => x.toString(), foo);
   if (tmp$1 !== undefined) {
     tmp.foo = tmp$1;
   }
@@ -31,13 +31,13 @@ let a_ = make(undefined, undefined);
 
 let b_ = make(42, undefined);
 
-Test_utils.eq("File \"gpr_1409_test.res\", line 24, characters 3-10", b_.foo, "42");
+Test_utils.eq("File \"gpr_1409_test.res\", line 23, characters 3-10", b_.foo, "42");
 
 console.log(Object.keys(a_));
 
 console.log(a, b, a_, b_);
 
-Test_utils.eq("File \"gpr_1409_test.res\", line 29, characters 3-10", Object.keys(a_).length, 0);
+Test_utils.eq("File \"gpr_1409_test.res\", line 28, characters 3-10", Object.keys(a_).length, 0);
 
 let test2 = {
   hi: 2
@@ -104,15 +104,15 @@ function test6(f, x) {
 }
 
 function keys(xs, ys) {
-  return String_set.equal(String_set.of_list(xs), String_set.of_list(Belt_List.fromArray(ys)));
+  return String_set.equal(String_set.of_list(xs), String_set.of_list(Stdlib_List.fromArray(ys)));
 }
 
-Test_utils.eq("File \"gpr_1409_test.res\", line 67, characters 3-10", keys({
+Test_utils.eq("File \"gpr_1409_test.res\", line 66, characters 3-10", keys({
   hd: "hi",
   tl: /* [] */0
 }, Object.keys(test3(undefined, undefined))), true);
 
-Test_utils.eq("File \"gpr_1409_test.res\", line 69, characters 3-10", keys({
+Test_utils.eq("File \"gpr_1409_test.res\", line 68, characters 3-10", keys({
   hd: "hi",
   tl: {
     hd: "_open",
@@ -120,7 +120,7 @@ Test_utils.eq("File \"gpr_1409_test.res\", line 69, characters 3-10", keys({
   }
 }, Object.keys(test3(2, undefined))), true);
 
-Test_utils.eq("File \"gpr_1409_test.res\", line 71, characters 3-10", keys({
+Test_utils.eq("File \"gpr_1409_test.res\", line 70, characters 3-10", keys({
   hd: "hi",
   tl: {
     hd: "_open",
@@ -132,20 +132,20 @@ Test_utils.eq("File \"gpr_1409_test.res\", line 71, characters 3-10", keys({
 }, Object.keys(test3(2, 2))), true);
 
 Mocha.describe("Gpr_1409_test", () => {
-  Mocha.test("test1", () => Test_utils.eq("File \"gpr_1409_test.res\", line 75, characters 7-14", b_.foo, "42"));
-  Mocha.test("test2", () => Test_utils.eq("File \"gpr_1409_test.res\", line 79, characters 7-14", Object.keys(a_).length, 0));
-  Mocha.test("test3", () => Test_utils.eq("File \"gpr_1409_test.res\", line 83, characters 7-14", keys({
+  Mocha.test("test1", () => Test_utils.eq("File \"gpr_1409_test.res\", line 74, characters 7-14", b_.foo, "42"));
+  Mocha.test("test2", () => Test_utils.eq("File \"gpr_1409_test.res\", line 78, characters 7-14", Object.keys(a_).length, 0));
+  Mocha.test("test3", () => Test_utils.eq("File \"gpr_1409_test.res\", line 82, characters 7-14", keys({
     hd: "hi",
     tl: /* [] */0
   }, Object.keys(test3(undefined, undefined))), true));
-  Mocha.test("test4", () => Test_utils.eq("File \"gpr_1409_test.res\", line 87, characters 7-14", keys({
+  Mocha.test("test4", () => Test_utils.eq("File \"gpr_1409_test.res\", line 86, characters 7-14", keys({
     hd: "hi",
     tl: {
       hd: "_open",
       tl: /* [] */0
     }
   }, Object.keys(test3(2, undefined))), true));
-  Mocha.test("test5", () => Test_utils.eq("File \"gpr_1409_test.res\", line 92, characters 6-13", keys({
+  Mocha.test("test5", () => Test_utils.eq("File \"gpr_1409_test.res\", line 91, characters 6-13", keys({
     hd: "hi",
     tl: {
       hd: "_open",
diff --git a/tests/tests/src/gpr_1409_test.res b/tests/tests/src/gpr_1409_test.res
index 758ac8ad5ac..6934e2c4b5d 100644
--- a/tests/tests/src/gpr_1409_test.res
+++ b/tests/tests/src/gpr_1409_test.res
@@ -1,6 +1,5 @@
 open Mocha
 open Test_utils
-open Belt
 
 /* type t */
 @get external foo: {..} => option<string> = "foo"
@@ -16,7 +15,7 @@ let map = (f, x) =>
   | Some(x) => Some(f(x))
   }
 
-let make = (~foo: option<int>=?, ()) => make(~foo=?map(Int.toString, foo), ())
+let make = (~foo: option<int>=?, ()) => make(~foo=?map(x => Int.toString(x), foo), ())
 
 let a_ = make()
 let b_ = make(~foo=42, ())
diff --git a/tests/tests/src/gpr_1701_test.mjs b/tests/tests/src/gpr_1701_test.mjs
index dcdc4574a14..aecc3ed504e 100644
--- a/tests/tests/src/gpr_1701_test.mjs
+++ b/tests/tests/src/gpr_1701_test.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_exceptions from "@rescript/runtime/lib/es6/Primitive_exceptions.mjs";
 
 let Foo = /* @__PURE__ */Primitive_exceptions.create("Gpr_1701_test.Foo");
@@ -41,7 +41,7 @@ function read_lines(inc) {
       }
     }
     if (l === undefined) {
-      return Belt_List.reverse(acc);
+      return Stdlib_List.reverse(acc);
     }
     _acc = {
       hd: l,
@@ -61,7 +61,7 @@ function read_lines2(inc) {
     } catch (raw_exn) {
       let exn = Primitive_exceptions.internalToException(raw_exn);
       if (exn.RE_EXN_ID === "End_of_file") {
-        return Belt_List.reverse(acc);
+        return Stdlib_List.reverse(acc);
       }
       throw exn;
     }
@@ -84,7 +84,7 @@ function read_lines3(inc) {
     } catch (raw_exn) {
       let exn = Primitive_exceptions.internalToException(raw_exn);
       if (exn.RE_EXN_ID === "End_of_file") {
-        return Belt_List.reverse(acc);
+        return Stdlib_List.reverse(acc);
       }
       throw exn;
     }
diff --git a/tests/tests/src/gpr_1701_test.res b/tests/tests/src/gpr_1701_test.res
index 6c8a9850454..d5c49713abe 100644
--- a/tests/tests/src/gpr_1701_test.res
+++ b/tests/tests/src/gpr_1701_test.res
@@ -1,5 +1,3 @@
-open Belt
-
 exception Foo
 
 let rec test = n =>
diff --git a/tests/tests/src/gpr_2487.mjs b/tests/tests/src/gpr_2487.mjs
index 9ef472624db..a47095f38dd 100644
--- a/tests/tests/src/gpr_2487.mjs
+++ b/tests/tests/src/gpr_2487.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
-let b = Belt_Array.eq([
+let b = Stdlib_Array.equal([
   1,
   2,
   3
diff --git a/tests/tests/src/gpr_2487.res b/tests/tests/src/gpr_2487.res
index 6cb3b8be39e..3930a1c9e7e 100644
--- a/tests/tests/src/gpr_2487.res
+++ b/tests/tests/src/gpr_2487.res
@@ -1,3 +1,3 @@
-module A = Belt.Array
+module A = Array
 
-let b = A.eq([1, 2, 3], [1, 2, 3], \"==")
+let b = A.equal([1, 2, 3], [1, 2, 3], \"==")
diff --git a/tests/tests/src/gpr_2608_test.mjs b/tests/tests/src/gpr_2608_test.mjs
index 4c62eb1cce4..ce8139163fc 100644
--- a/tests/tests/src/gpr_2608_test.mjs
+++ b/tests/tests/src/gpr_2608_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 let oppHeroes = {
   hd: 0,
@@ -11,22 +11,22 @@ let oppHeroes = {
 
 let huntGrootCondition = false;
 
-if (Belt_List.length(/* [] */0) > 0) {
-  let x = Belt_List.filter(oppHeroes, h => Belt_List.headExn(/* [] */0) <= 1000);
-  huntGrootCondition = Belt_List.length(x) === 0;
+if (Stdlib_List.length(/* [] */0) > 0) {
+  let x = Stdlib_List.filter(oppHeroes, h => Stdlib_List.headExn(/* [] */0) <= 1000);
+  huntGrootCondition = Stdlib_List.length(x) === 0;
 }
 
 let huntGrootCondition2 = true;
 
-if (Belt_List.length(/* [] */0) < 0) {
-  let x$1 = Belt_List.filter(oppHeroes, h => Belt_List.headExn(/* [] */0) <= 1000);
-  huntGrootCondition2 = Belt_List.length(x$1) === 0;
+if (Stdlib_List.length(/* [] */0) < 0) {
+  let x$1 = Stdlib_List.filter(oppHeroes, h => Stdlib_List.headExn(/* [] */0) <= 1000);
+  huntGrootCondition2 = Stdlib_List.length(x$1) === 0;
 }
 
 Mocha.describe("Gpr_2608_test", () => {
   Mocha.test("huntGroot conditions", () => {
-    Test_utils.eq("File \"gpr_2608_test.res\", line 22, characters 7-14", huntGrootCondition, false);
-    Test_utils.eq("File \"gpr_2608_test.res\", line 23, characters 7-14", huntGrootCondition2, true);
+    Test_utils.eq("File \"gpr_2608_test.res\", line 21, characters 7-14", huntGrootCondition, false);
+    Test_utils.eq("File \"gpr_2608_test.res\", line 22, characters 7-14", huntGrootCondition2, true);
   });
 });
 
diff --git a/tests/tests/src/gpr_2608_test.res b/tests/tests/src/gpr_2608_test.res
index 916b31dd2e7..01719eade00 100644
--- a/tests/tests/src/gpr_2608_test.res
+++ b/tests/tests/src/gpr_2608_test.res
@@ -1,4 +1,3 @@
-open Belt
 open Mocha
 open Test_utils
 
diff --git a/tests/tests/src/gpr_3931_test.mjs b/tests/tests/src/gpr_3931_test.mjs
index ac4b4e07619..88806cb26d9 100644
--- a/tests/tests/src/gpr_3931_test.mjs
+++ b/tests/tests/src/gpr_3931_test.mjs
@@ -1,6 +1,5 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Primitive_module from "@rescript/runtime/lib/es6/Primitive_module.mjs";
 
 let PA = Primitive_module.init([
@@ -28,7 +27,7 @@ let P = Primitive_module.init([
 });
 
 function print(a) {
-  Belt_Array.forEach(a, P.print);
+  a.forEach(P.print);
 }
 
 Primitive_module.update({
diff --git a/tests/tests/src/gpr_3931_test.res b/tests/tests/src/gpr_3931_test.res
index 41fdb8ba789..450252cec37 100644
--- a/tests/tests/src/gpr_3931_test.res
+++ b/tests/tests/src/gpr_3931_test.res
@@ -3,7 +3,7 @@ module rec PA: {
 } = {
   /* let () = P.print 3 */
   let print = {
-    let iter = Belt.Array.forEach(_, P.print)
+    let iter = Array.forEach(_, P.print)
     a => iter(a)
   }
 }
diff --git a/tests/tests/src/gpr_4274_test.mjs b/tests/tests/src/gpr_4274_test.mjs
index c371ba64e7b..c326238a3b9 100644
--- a/tests/tests/src/gpr_4274_test.mjs
+++ b/tests/tests/src/gpr_4274_test.mjs
@@ -1,7 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 let N = {};
 
@@ -13,7 +12,7 @@ function f(X, xs) {
   });
 }
 
-Belt_List.forEach({
+Stdlib_List.forEach({
   hd: {
     x: 3
   },
@@ -28,7 +27,7 @@ let bar = [{
     foo: "bar"
   }];
 
-Belt_Array.map(bar, b => b.foo);
+bar.map(b => b.foo);
 
 export {
   N,
diff --git a/tests/tests/src/gpr_4274_test.res b/tests/tests/src/gpr_4274_test.res
index 12729cf1d7b..6370177087a 100644
--- a/tests/tests/src/gpr_4274_test.res
+++ b/tests/tests/src/gpr_4274_test.res
@@ -10,11 +10,11 @@ module type X = {
 /* type annotation here interferes.. */
 let f = (module(X: X), xs: array<N.t>) => X.forEach(xs, {X.i: x => Console.log(x.x)})
 
-Belt.List.forEach(list{{N.x: 3}}, x => Console.log(x.x))
+List.forEach(list{{N.x: 3}}, x => Console.log(x.x))
 
 module Foo = {
   type record = {foo: string}
 }
 let bar = [{Foo.foo: @reason.raw_literal("bar") "bar"}]
 
-let _ = Belt.Array.map(bar, b => b.foo)
+let _ = Array.map(bar, b => b.foo)
diff --git a/tests/tests/src/hello_res.mjs b/tests/tests/src/hello_res.mjs
index 82501f0936c..8a1f043af4e 100644
--- a/tests/tests/src/hello_res.mjs
+++ b/tests/tests/src/hello_res.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
-let b = Belt_List.length({
+let b = Stdlib_List.length({
   hd: 1,
   tl: {
     hd: 2,
@@ -17,7 +17,7 @@ let a = b - 1 | 0;
 
 console.log("hello, res");
 
-Belt_List.add(/* [] */0, Belt_List.length({
+Stdlib_List.add(/* [] */0, Stdlib_List.length({
   hd: 1,
   tl: {
     hd: 2,
diff --git a/tests/tests/src/hello_res.res b/tests/tests/src/hello_res.res
index 788c822dee0..abc71fef1a9 100644
--- a/tests/tests/src/hello_res.res
+++ b/tests/tests/src/hello_res.res
@@ -4,8 +4,6 @@
   ],
 })
 
-open Belt
-
 let b = List.length(list{1, 2, 3})
 let a = b - 1
 Console.log("hello, res")
diff --git a/tests/tests/src/inline_map2_test.mjs b/tests/tests/src/inline_map2_test.mjs
index 43a7b917061..8e98a44c5ca 100644
--- a/tests/tests/src/inline_map2_test.mjs
+++ b/tests/tests/src/inline_map2_test.mjs
@@ -1,9 +1,9 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 import * as Primitive_string from "@rescript/runtime/lib/es6/Primitive_string.mjs";
@@ -1223,7 +1223,7 @@ let IntMap = {
   choose: min_binding
 };
 
-let m = Belt_List.reduceReverse({
+let m = Stdlib_List.reduceReverse({
   hd: [
     10,
     /* 'a' */97
@@ -1875,7 +1875,7 @@ let SMap = {
   choose: min_binding$1
 };
 
-let s = Belt_List.reduceReverse({
+let s = Stdlib_List.reduceReverse({
   hd: [
     "10",
     /* 'a' */97
@@ -1902,8 +1902,8 @@ let s = Belt_List.reduceReverse({
 }, "Empty", (acc, param) => add$1(param[0], param[1], acc));
 
 Mocha.describe("Inline_map2_test", () => {
-  Mocha.test("assertion1", () => Test_utils.eq("File \"inline_map2_test.res\", line 480, characters 30-37", find(10, m), /* 'a' */97));
-  Mocha.test("assertion2", () => Test_utils.eq("File \"inline_map2_test.res\", line 481, characters 30-37", find$1("10", s), /* 'a' */97));
+  Mocha.test("assertion1", () => Test_utils.eq("File \"inline_map2_test.res\", line 478, characters 30-37", find(10, m), /* 'a' */97));
+  Mocha.test("assertion2", () => Test_utils.eq("File \"inline_map2_test.res\", line 479, characters 30-37", find$1("10", s), /* 'a' */97));
 });
 
 let eq = Test_utils.eq;
diff --git a/tests/tests/src/inline_map2_test.res b/tests/tests/src/inline_map2_test.res
index 84778b762dd..d850e2bd581 100644
--- a/tests/tests/src/inline_map2_test.res
+++ b/tests/tests/src/inline_map2_test.res
@@ -459,21 +459,19 @@ module IntMap = Make({
 
 let empty = IntMap.empty
 
-let m = Belt.List.reduceReverse(list{(10, 'a'), (3, 'b'), (7, 'c'), (20, 'd')}, empty, (
-  acc,
-  (k, v),
-) => IntMap.add(k, v, acc))
+let m = List.reduceReverse(list{(10, 'a'), (3, 'b'), (7, 'c'), (20, 'd')}, empty, (acc, (k, v)) =>
+  IntMap.add(k, v, acc)
+)
 
 module SMap = Make({
   type t = string
   let compare = (x: t, y) => compare(x, y)
 })
 
-let s = Belt.List.reduceReverse(
-  list{("10", 'a'), ("3", 'b'), ("7", 'c'), ("20", 'd')},
-  SMap.empty,
-  (acc, (k, v)) => SMap.add(k, v, acc),
-)
+let s = List.reduceReverse(list{("10", 'a'), ("3", 'b'), ("7", 'c'), ("20", 'd')}, SMap.empty, (
+  acc,
+  (k, v),
+) => SMap.add(k, v, acc))
 @val("console.log") external log: 'a => unit = ""
 
 describe(__MODULE__, () => {
diff --git a/tests/tests/src/inline_map_demo.mjs b/tests/tests/src/inline_map_demo.mjs
index 1e1d74398cf..17790a7b1db 100644
--- a/tests/tests/src/inline_map_demo.mjs
+++ b/tests/tests/src/inline_map_demo.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 
 function height(x) {
@@ -137,7 +137,7 @@ function add(x, data, tree) {
   }
 }
 
-let m = Belt_List.reduceReverse({
+let m = Stdlib_List.reduceReverse({
   hd: [
     10,
     /* 'a' */97
@@ -182,7 +182,7 @@ function find(px, _x) {
 }
 
 Mocha.describe("Inline_map_demo", () => {
-  Mocha.test("find", () => Test_utils.eq("File \"inline_map_demo.res\", line 142, characters 24-31", find(10, m), /* 'a' */97));
+  Mocha.test("find", () => Test_utils.eq("File \"inline_map_demo.res\", line 141, characters 24-31", find(10, m), /* 'a' */97));
 });
 
 /* m Not a pure module */
diff --git a/tests/tests/src/inline_map_demo.res b/tests/tests/src/inline_map_demo.res
index edda67595cd..691ac825fe0 100644
--- a/tests/tests/src/inline_map_demo.res
+++ b/tests/tests/src/inline_map_demo.res
@@ -111,10 +111,9 @@ let empty = Empty
    No assumption on the heights of l and r. */
 
 /* end */
-let m = Belt.List.reduceReverse(list{(10, 'a'), (3, 'b'), (7, 'c'), (20, 'd')}, empty, (
-  acc,
-  (k, v),
-) => add(k, v, acc))
+let m = List.reduceReverse(list{(10, 'a'), (3, 'b'), (7, 'c'), (20, 'd')}, empty, (acc, (k, v)) =>
+  add(k, v, acc)
+)
 
 let rec find = (px, x) =>
   switch x {
diff --git a/tests/tests/src/inline_map_test.mjs b/tests/tests/src/inline_map_test.mjs
index 92a0d49f050..56120f4fd1c 100644
--- a/tests/tests/src/inline_map_test.mjs
+++ b/tests/tests/src/inline_map_test.mjs
@@ -1,9 +1,9 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 
 function height(x) {
@@ -124,7 +124,7 @@ function find(x, _x_) {
   };
 }
 
-let m = Belt_List.reduceReverse({
+let m = Stdlib_List.reduceReverse({
   hd: [
     10,
     /* 'a' */97
@@ -151,7 +151,7 @@ let m = Belt_List.reduceReverse({
 }, "Empty", (acc, param) => add(param[0], param[1], acc));
 
 Mocha.describe("Inline_map_test", () => {
-  Mocha.test("inline map test", () => Test_utils.eq("File \"inline_map_test.res\", line 420, characters 7-14", find(10, m), /* 'a' */97));
+  Mocha.test("inline map test", () => Test_utils.eq("File \"inline_map_test.res\", line 419, characters 7-14", find(10, m), /* 'a' */97));
 });
 
 /* m Not a pure module */
diff --git a/tests/tests/src/inline_map_test.res b/tests/tests/src/inline_map_test.res
index fdf1d98c204..970eb0101f0 100644
--- a/tests/tests/src/inline_map_test.res
+++ b/tests/tests/src/inline_map_test.res
@@ -408,10 +408,9 @@ let bindings = s => bindings_aux(list{}, s)
 let choose = min_binding
 
 /* end */
-let m = Belt.List.reduceReverse(list{(10, 'a'), (3, 'b'), (7, 'c'), (20, 'd')}, empty, (
-  acc,
-  (k, v),
-) => add(k, v, acc))
+let m = List.reduceReverse(list{(10, 'a'), (3, 'b'), (7, 'c'), (20, 'd')}, empty, (acc, (k, v)) =>
+  add(k, v, acc)
+)
 
 @val("console.log") external log: 'a => unit = ""
 
diff --git a/tests/tests/src/inline_record_test.mjs b/tests/tests/src/inline_record_test.mjs
index cc3e552a0b4..a3890323766 100644
--- a/tests/tests/src/inline_record_test.mjs
+++ b/tests/tests/src/inline_record_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_exceptions from "@rescript/runtime/lib/es6/Primitive_exceptions.mjs";
 
 let v = {
@@ -24,9 +24,9 @@ let v1 = {
 
 function f(x) {
   if (x.TAG === "A0") {
-    return Belt_List.reduceReverse(x.more, x.lbl, (a, b) => a + b | 0);
+    return Stdlib_List.reduceReverse(x.more, x.lbl, (a, b) => a + b | 0);
   } else {
-    return Belt_List.reduceReverse(x.more, 0, (a, b) => a + b | 0);
+    return Stdlib_List.reduceReverse(x.more, 0, (a, b) => a + b | 0);
   }
 }
 
diff --git a/tests/tests/src/inline_record_test.res b/tests/tests/src/inline_record_test.res
index b98d04e1537..89ad82934e4 100644
--- a/tests/tests/src/inline_record_test.res
+++ b/tests/tests/src/inline_record_test.res
@@ -10,8 +10,8 @@ let v1 = A1({more: list{1, 2}})
 
 let f = (x: t0) =>
   switch x {
-  | A0({lbl, more}) => more->Belt.List.reduceReverse(lbl, (a, b) => a + b)
-  | A1({more}) => more->Belt.List.reduceReverse(0, (a, b) => a + b)
+  | A0({lbl, more}) => more->List.reduceReverse(lbl, (a, b) => a + b)
+  | A1({more}) => more->List.reduceReverse(0, (a, b) => a + b)
   }
 
 type t1 =
diff --git a/tests/tests/src/label_uncurry.mjs b/tests/tests/src/label_uncurry.mjs
index 3566a35c630..1714c8b7ecf 100644
--- a/tests/tests/src/label_uncurry.mjs
+++ b/tests/tests/src/label_uncurry.mjs
@@ -1,13 +1,13 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Int from "@rescript/runtime/lib/es6/Belt_Int.mjs";
+import * as Stdlib_Int from "@rescript/runtime/lib/es6/Stdlib_Int.mjs";
 
 function f(x) {
   return x;
 }
 
 function u(x, y) {
-  let y$1 = Belt_Int.fromString(y);
+  let y$1 = Stdlib_Int.fromString(y);
   if (y$1 !== undefined) {
     return x + y$1 | 0;
   }
diff --git a/tests/tests/src/label_uncurry.res b/tests/tests/src/label_uncurry.res
index 31f14ca885e..e27ecd80592 100644
--- a/tests/tests/src/label_uncurry.res
+++ b/tests/tests/src/label_uncurry.res
@@ -5,7 +5,7 @@ type u = (~x: int, ~y: string) => option<int>
 let f = (x: t): u => x
 
 let u: u = (~x, ~y) =>
-  switch Belt.Int.fromString(y) {
+  switch Int.fromString(y) {
   | Some(y) => Some(x + y)
   | None => None
   }
diff --git a/tests/tests/src/loop_control_test.mjs b/tests/tests/src/loop_control_test.mjs
index 71ca7f6a085..cc06a3a4751 100644
--- a/tests/tests/src/loop_control_test.mjs
+++ b/tests/tests/src/loop_control_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 Mocha.describe("Loop_control_test", () => {
   Mocha.test("while loop break and continue", () => {
@@ -25,7 +25,7 @@ Mocha.describe("Loop_control_test", () => {
       1,
       3,
       4
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
   Mocha.test("switch inside while targets the loop", () => {
     let values = /* [] */0;
@@ -50,7 +50,7 @@ Mocha.describe("Loop_control_test", () => {
       1,
       3,
       4
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
   Mocha.test("string switch inside while targets the loop via JS switch", () => {
     let values = /* [] */0;
@@ -77,7 +77,7 @@ Mocha.describe("Loop_control_test", () => {
       1,
       3,
       4
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
   Mocha.test("for loop break and continue", () => {
     let values = /* [] */0;
@@ -97,7 +97,7 @@ Mocha.describe("Loop_control_test", () => {
       0,
       2,
       3
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
   Mocha.test("braced break expression in value position compiles", () => {
     let reached = false;
@@ -121,7 +121,7 @@ Mocha.describe("Loop_control_test", () => {
       0,
       2,
       3
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
   Mocha.test("switch inside for targets the loop", () => {
     let values = /* [] */0;
@@ -143,7 +143,7 @@ Mocha.describe("Loop_control_test", () => {
       0,
       2,
       3
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
   Mocha.test("string switch inside for targets the loop via JS switch", () => {
     let values = /* [] */0;
@@ -167,7 +167,7 @@ Mocha.describe("Loop_control_test", () => {
       0,
       2,
       3
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
   Mocha.test("for..of loop break and continue", () => {
     let values = /* [] */0;
@@ -194,7 +194,7 @@ Mocha.describe("Loop_control_test", () => {
       0,
       2,
       3
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
   Mocha.test("switch inside for..of targets the loop", () => {
     let values = /* [] */0;
@@ -223,7 +223,7 @@ Mocha.describe("Loop_control_test", () => {
       0,
       2,
       3
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
   Mocha.test("string switch inside for..of targets the loop via JS switch", () => {
     let values = /* [] */0;
@@ -254,7 +254,7 @@ Mocha.describe("Loop_control_test", () => {
       0,
       2,
       3
-    ], Belt_List.toArray(Belt_List.reverse(values)));
+    ], Stdlib_List.toArray(Stdlib_List.reverse(values)));
   });
 });
 
diff --git a/tests/tests/src/loop_control_test.res b/tests/tests/src/loop_control_test.res
index 715b32f446b..45e26aa028e 100644
--- a/tests/tests/src/loop_control_test.res
+++ b/tests/tests/src/loop_control_test.res
@@ -20,7 +20,7 @@ describe(__MODULE__, () => {
       values := list{i.contents, ...values.contents}
     }
 
-    eq(__LOC__, [1, 3, 4], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [1, 3, 4], values.contents->List.reverse->List.toArray)
   })
 
   test("switch inside while targets the loop", () => {
@@ -37,7 +37,7 @@ describe(__MODULE__, () => {
       }
     }
 
-    eq(__LOC__, [1, 3, 4], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [1, 3, 4], values.contents->List.reverse->List.toArray)
   })
 
   // Keep a JS `switch` in the generated output so this exercises labeled loop control.
@@ -61,7 +61,7 @@ describe(__MODULE__, () => {
       }
     }
 
-    eq(__LOC__, [1, 3, 4], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [1, 3, 4], values.contents->List.reverse->List.toArray)
   })
 
   test("for loop break and continue", () => {
@@ -79,7 +79,7 @@ describe(__MODULE__, () => {
       values := list{i, ...values.contents}
     }
 
-    eq(__LOC__, [0, 2, 3], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [0, 2, 3], values.contents->List.reverse->List.toArray)
   })
 
   test("braced break expression in value position compiles", () => {
@@ -108,7 +108,7 @@ describe(__MODULE__, () => {
       values := list{i, ...values.contents}
     }
 
-    eq(__LOC__, [0, 2, 3], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [0, 2, 3], values.contents->List.reverse->List.toArray)
   })
 
   test("switch inside for targets the loop", () => {
@@ -122,7 +122,7 @@ describe(__MODULE__, () => {
       }
     }
 
-    eq(__LOC__, [0, 2, 3], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [0, 2, 3], values.contents->List.reverse->List.toArray)
   })
 
   // Keep a JS `switch` in the generated output so this exercises labeled loop control.
@@ -143,7 +143,7 @@ describe(__MODULE__, () => {
       }
     }
 
-    eq(__LOC__, [0, 2, 3], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [0, 2, 3], values.contents->List.reverse->List.toArray)
   })
 
   test("for..of loop break and continue", () => {
@@ -161,7 +161,7 @@ describe(__MODULE__, () => {
       values := list{i, ...values.contents}
     }
 
-    eq(__LOC__, [0, 2, 3], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [0, 2, 3], values.contents->List.reverse->List.toArray)
   })
 
   test("switch inside for..of targets the loop", () => {
@@ -175,7 +175,7 @@ describe(__MODULE__, () => {
       }
     }
 
-    eq(__LOC__, [0, 2, 3], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [0, 2, 3], values.contents->List.reverse->List.toArray)
   })
 
   // Keep a JS `switch` in the generated output so this exercises labeled loop control.
@@ -196,6 +196,6 @@ describe(__MODULE__, () => {
       }
     }
 
-    eq(__LOC__, [0, 2, 3], values.contents->Belt.List.reverse->Belt.List.toArray)
+    eq(__LOC__, [0, 2, 3], values.contents->List.reverse->List.toArray)
   })
 })
diff --git a/tests/tests/src/mario_game.mjs b/tests/tests/src/mario_game.mjs
index 0857748d8a1..1f175463ad5 100644
--- a/tests/tests/src/mario_game.mjs
+++ b/tests/tests/src/mario_game.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Primitive_float from "@rescript/runtime/lib/es6/Primitive_float.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
@@ -951,7 +951,7 @@ function update_player(player, keys, context) {
   let prev_jumping = player.jumping;
   let prev_dir = player.dir;
   let prev_vx = Math.abs(player.vel.x);
-  Belt_List.forEach(keys, extra => {
+  Stdlib_List.forEach(keys, extra => {
     let lr_acc = player.vel.x * 0.2;
     switch (extra) {
       case "CLeft" :
@@ -1463,8 +1463,8 @@ function clear_canvas(canvas) {
 }
 
 function hud(canvas, score, coins) {
-  let score_string = String(score);
-  let coin_string = String(coins);
+  let score_string = score.toString();
+  let coin_string = coins.toString();
   let context = canvas.getContext("2d");
   context.font = "10px 'Press Start 2P'";
   context.fillText("Score: " + score_string, canvas.width - 140, 18);
@@ -2073,7 +2073,7 @@ function process_collision(dir, c1, c2, state) {
 
 function broad_phase(collid, all_collids, state) {
   let obj = collid._2;
-  return Belt_List.filter(all_collids, c => {
+  return Stdlib_List.filter(all_collids, c => {
     if (in_viewport(state.vpt, obj.pos) || is_player(collid)) {
       return true;
     } else {
@@ -2193,7 +2193,7 @@ function translate_keys() {
     hd: ctrls_0,
     tl: ctrls_1
   };
-  return Belt_List.reduceReverse(ctrls, /* [] */0, (a, x) => {
+  return Stdlib_List.reduceReverse(ctrls, /* [] */0, (a, x) => {
     if (x[0]) {
       return {
         hd: x[1],
@@ -2287,10 +2287,10 @@ function update_loop(canvas, param, map_dim) {
       multiplier: state.multiplier,
       game_over: state.game_over
     };
-    Belt_List.forEach(objs, obj => {
+    Stdlib_List.forEach(objs, obj => {
       run_update_collid(state$1, obj, objs);
     });
-    Belt_List.forEach(parts, part => {
+    Stdlib_List.forEach(parts, part => {
       process(part);
       let x = part.pos.x - state$1.vpt.pos.x;
       let y = part.pos.y - state$1.vpt.pos.y;
@@ -3264,7 +3264,7 @@ function inc_counter(param) {
 }
 
 function preload(param) {
-  return Belt_List.map({
+  return Stdlib_List.map({
     hd: "blocks.png",
     tl: {
       hd: "items.png",
diff --git a/tests/tests/src/mario_game.res b/tests/tests/src/mario_game.res
index 098fe281542..7d8c205e458 100644
--- a/tests/tests/src/mario_game.res
+++ b/tests/tests/src/mario_game.res
@@ -1,7 +1,5 @@
 @@config({flags: ["-w", "a", "-bs-no-bin-annot"]})
 
-open Belt
-
 module Random = {
   let self_init = () => ()
 
diff --git a/tests/tests/src/module_alias_test.mjs b/tests/tests/src/module_alias_test.mjs
index dcaa6aeb854..e4bfaf7004a 100644
--- a/tests/tests/src/module_alias_test.mjs
+++ b/tests/tests/src/module_alias_test.mjs
@@ -1,13 +1,13 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function f(x) {
   console.log(x);
-  console.log(Belt_List.length(x));
-  return Belt_List;
+  console.log(Stdlib_List.length(x));
+  return Stdlib_List;
 }
 
 let h = f(/* [] */0);
@@ -23,10 +23,10 @@ let a = h.length({
   }
 });
 
-Test_utils.eq("File \"module_alias_test.res\", line 26, characters 3-10", a, 3);
+Test_utils.eq("File \"module_alias_test.res\", line 25, characters 3-10", a, 3);
 
 Mocha.describe("Module_alias_test", () => {
-  Mocha.test("module_alias_test", () => Test_utils.eq("File \"module_alias_test.res\", line 29, characters 7-14", a, 3));
+  Mocha.test("module_alias_test", () => Test_utils.eq("File \"module_alias_test.res\", line 28, characters 7-14", a, 3));
 });
 
 let N;
diff --git a/tests/tests/src/module_alias_test.res b/tests/tests/src/module_alias_test.res
index d454669c4ab..8c3b3401cdb 100644
--- a/tests/tests/src/module_alias_test.res
+++ b/tests/tests/src/module_alias_test.res
@@ -1,6 +1,5 @@
 open Mocha
 open Test_utils
-open Belt
 
 module N = List
 
diff --git a/tests/tests/src/module_missing_conversion.mjs b/tests/tests/src/module_missing_conversion.mjs
index 6b3ff81d7e3..e45e16d66bc 100644
--- a/tests/tests/src/module_missing_conversion.mjs
+++ b/tests/tests/src/module_missing_conversion.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 import * as Stdlib_String from "@rescript/runtime/lib/es6/Stdlib_String.mjs";
 
 function f(x) {
@@ -8,80 +8,31 @@ function f(x) {
 }
 
 let XX = {
-  get: Belt_Array.get,
-  getExn: Belt_Array.getExn,
-  getOrThrow: Belt_Array.getOrThrow,
-  set: Belt_Array.set,
-  setExn: Belt_Array.setExn,
-  setOrThrow: Belt_Array.setOrThrow,
-  shuffleInPlace: Belt_Array.shuffleInPlace,
-  shuffle: Belt_Array.shuffle,
-  reverseInPlace: Belt_Array.reverseInPlace,
-  reverse: Belt_Array.reverse,
-  make: Belt_Array.make,
-  range: Belt_Array.range,
-  rangeBy: Belt_Array.rangeBy,
-  makeByU: Belt_Array.makeByU,
-  makeBy: Belt_Array.makeBy,
-  makeByAndShuffleU: Belt_Array.makeByAndShuffleU,
-  makeByAndShuffle: Belt_Array.makeByAndShuffle,
-  zip: Belt_Array.zip,
-  zipByU: Belt_Array.zipByU,
-  zipBy: Belt_Array.zipBy,
-  unzip: Belt_Array.unzip,
-  concat: Belt_Array.concat,
-  concatMany: Belt_Array.concatMany,
-  slice: Belt_Array.slice,
-  sliceToEnd: Belt_Array.sliceToEnd,
-  fill: Belt_Array.fill,
-  blit: Belt_Array.blit,
-  blitUnsafe: Belt_Array.blitUnsafe,
-  forEachU: Belt_Array.forEachU,
-  forEach: Belt_Array.forEach,
-  mapU: Belt_Array.mapU,
-  map: Belt_Array.map,
-  flatMapU: Belt_Array.flatMapU,
-  flatMap: Belt_Array.flatMap,
-  getByU: Belt_Array.getByU,
-  getBy: Belt_Array.getBy,
-  getIndexByU: Belt_Array.getIndexByU,
-  getIndexBy: Belt_Array.getIndexBy,
-  keepU: Belt_Array.keepU,
-  keep: Belt_Array.keep,
-  keepWithIndexU: Belt_Array.keepWithIndexU,
-  keepWithIndex: Belt_Array.keepWithIndex,
-  keepMapU: Belt_Array.keepMapU,
-  keepMap: Belt_Array.keepMap,
-  forEachWithIndexU: Belt_Array.forEachWithIndexU,
-  forEachWithIndex: Belt_Array.forEachWithIndex,
-  mapWithIndexU: Belt_Array.mapWithIndexU,
-  mapWithIndex: Belt_Array.mapWithIndex,
-  partitionU: Belt_Array.partitionU,
-  partition: Belt_Array.partition,
-  reduceU: Belt_Array.reduceU,
-  reduce: Belt_Array.reduce,
-  reduceReverseU: Belt_Array.reduceReverseU,
-  reduceReverse: Belt_Array.reduceReverse,
-  reduceReverse2U: Belt_Array.reduceReverse2U,
-  reduceReverse2: Belt_Array.reduceReverse2,
-  reduceWithIndexU: Belt_Array.reduceWithIndexU,
-  reduceWithIndex: Belt_Array.reduceWithIndex,
-  joinWithU: Belt_Array.joinWithU,
-  joinWith: Belt_Array.joinWith,
-  someU: Belt_Array.someU,
-  some: Belt_Array.some,
-  everyU: Belt_Array.everyU,
-  every: Belt_Array.every,
-  every2U: Belt_Array.every2U,
-  every2: Belt_Array.every2,
-  some2U: Belt_Array.some2U,
-  some2: Belt_Array.some2,
-  cmpU: Belt_Array.cmpU,
-  cmp: Belt_Array.cmp,
-  eqU: Belt_Array.eqU,
-  eq: Belt_Array.eq,
-  initU: Belt_Array.initU,
-  init: Belt_Array.init,
+  make: Stdlib_Array.make,
+  fromInitializer: Stdlib_Array.fromInitializer,
+  equal: Stdlib_Array.equal,
+  compare: Stdlib_Array.compare,
+  isEmpty: Stdlib_Array.isEmpty,
+  concatAll: Stdlib_Array.concatAll,
+  indexOfOpt: Stdlib_Array.indexOfOpt,
+  lastIndexOfOpt: Stdlib_Array.lastIndexOfOpt,
+  reduce: Stdlib_Array.reduce,
+  reduceWithIndex: Stdlib_Array.reduceWithIndex,
+  reduceRight: Stdlib_Array.reduceRight,
+  reduceRightWithIndex: Stdlib_Array.reduceRightWithIndex,
+  findIndexOpt: Stdlib_Array.findIndexOpt,
+  findLastIndexOpt: Stdlib_Array.findLastIndexOpt,
+  filterMap: Stdlib_Array.filterMap,
+  filterMapWithIndex: Stdlib_Array.filterMapWithIndex,
+  keepSome: Stdlib_Array.keepSome,
+  toShuffled: Stdlib_Array.toShuffled,
+  shuffle: Stdlib_Array.shuffle,
+  findMap: Stdlib_Array.findMap,
+  zip: Stdlib_Array.zip,
+  zipBy: Stdlib_Array.zipBy,
+  partition: Stdlib_Array.partition,
+  unzip: Stdlib_Array.unzip,
+  last: Stdlib_Array.last,
   f: f
 };
 
diff --git a/tests/tests/src/module_missing_conversion.res b/tests/tests/src/module_missing_conversion.res
index 728fdb345f5..8c80eb177cf 100644
--- a/tests/tests/src/module_missing_conversion.res
+++ b/tests/tests/src/module_missing_conversion.res
@@ -1,7 +1,7 @@
 module type S = module type of String
 
 module XX = {
-  include Belt.Array
+  include Array
   let f = x => x
 }
 let u = [module(String: S)]
diff --git a/tests/tests/src/module_test.mjs b/tests/tests/src/module_test.mjs
index 8dc29be36ed..ccbf81e6072 100644
--- a/tests/tests/src/module_test.mjs
+++ b/tests/tests/src/module_test.mjs
@@ -1,15 +1,15 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function length(param) {
   return 3;
 }
 
 Mocha.describe("Module_test", () => {
-  Mocha.test("list_length", () => Test_utils.eq("File \"module_test.res\", line 8, characters 31-38", 2, Belt_List.length({
+  Mocha.test("list_length", () => Test_utils.eq("File \"module_test.res\", line 8, characters 31-38", 2, Stdlib_List.length({
     hd: 1,
     tl: {
       hd: 2,
diff --git a/tests/tests/src/module_test.res b/tests/tests/src/module_test.res
index 3304314d331..80c4c19239d 100644
--- a/tests/tests/src/module_test.res
+++ b/tests/tests/src/module_test.res
@@ -5,6 +5,6 @@ let length = _ => 3
 
 /* Test name collision */
 describe(__MODULE__, () => {
-  test("list_length", () => eq(__LOC__, 2, Belt.List.length(list{1, 2})))
+  test("list_length", () => eq(__LOC__, 2, List.length(list{1, 2})))
   test("length", () => eq(__LOC__, 3, length(list{1, 2})))
 })
diff --git a/tests/tests/src/nested_module_alias.mjs b/tests/tests/src/nested_module_alias.mjs
index 7235537862e..c01e3e625e3 100644
--- a/tests/tests/src/nested_module_alias.mjs
+++ b/tests/tests/src/nested_module_alias.mjs
@@ -1,11 +1,11 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function v(x) {
   return [
-    Belt_List.length(x),
-    Belt_List.length(x)
+    Stdlib_List.length(x),
+    Stdlib_List.length(x)
   ];
 }
 
diff --git a/tests/tests/src/nested_module_alias.res b/tests/tests/src/nested_module_alias.res
index 38010d1b575..56992831fd5 100644
--- a/tests/tests/src/nested_module_alias.res
+++ b/tests/tests/src/nested_module_alias.res
@@ -1,7 +1,7 @@
-module L = Belt.List
+module L = List
 
 let v = x => {
-  module H = Belt.List
+  module H = List
   module U = L
   (H.length(x), U.length(x))
 }
diff --git a/tests/tests/src/obj_literal_ppx.res b/tests/tests/src/obj_literal_ppx.res
index 16487495d8d..50b30a939bd 100644
--- a/tests/tests/src/obj_literal_ppx.res
+++ b/tests/tests/src/obj_literal_ppx.res
@@ -2,7 +2,7 @@ let a = {"x": 3, "y": [1]}
 
 let b = {"x": 3, "y": [1], "z": 3, "u": (x, y) => x + y}
 
-let f = obj => obj["x"] + Belt.Array.length(obj["y"])
+let f = obj => obj["x"] + Array.length(obj["y"])
 
 let u = f(a)
 
diff --git a/tests/tests/src/offset.res b/tests/tests/src/offset.res
index c6ed1f247b3..98eb315ae4c 100644
--- a/tests/tests/src/offset.res
+++ b/tests/tests/src/offset.res
@@ -16,7 +16,7 @@ module M = {
   let x = 0
   let x = 1
 
-  module Set = Belt.Set.String
+  module Set = Stdlib.Set
 }
 
 include M
diff --git a/tests/tests/src/option_repr_test.mjs b/tests/tests/src/option_repr_test.mjs
index a872ce60e45..5ef9b6b614c 100644
--- a/tests/tests/src/option_repr_test.mjs
+++ b/tests/tests/src/option_repr_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
@@ -88,12 +88,12 @@ function f12(x) {
   return x;
 }
 
-let length_8_id = Belt_List.makeBy(8, x => x);
+let length_8_id = Stdlib_List.fromInitializer(8, x => x);
 
-let length_10_id = Belt_List.makeBy(10, x => x);
+let length_10_id = Stdlib_List.fromInitializer(10, x => x);
 
 function f13$1() {
-  return Primitive_object.equal(Belt_List.take(length_10_id, 8), {
+  return Primitive_object.equal(Stdlib_List.take(length_10_id, 8), {
     hd: 1,
     tl: {
       hd: 2,
@@ -140,7 +140,7 @@ function neqx(a, b) {
 }
 
 function all_true(xs) {
-  return Belt_List.every(xs, x => x);
+  return Stdlib_List.every(xs, x => x);
 }
 
 Mocha.describe("Option_repr_test", () => {
@@ -157,7 +157,7 @@ Mocha.describe("Option_repr_test", () => {
       hd: xs_0,
       tl: /* [] */0
     };
-    Test_utils.ok("File \"option_repr_test.res\", line 125, characters 7-14", Belt_List.every(xs, x => x));
+    Test_utils.ok("File \"option_repr_test.res\", line 125, characters 7-14", Stdlib_List.every(xs, x => x));
   });
   Mocha.test("option less than operations", () => {
     let xs_0 = Primitive_object.lessthan(Primitive_option.some(undefined), 3) && Primitive_object.greaterthan(3, Primitive_option.some(undefined));
@@ -196,7 +196,7 @@ Mocha.describe("Option_repr_test", () => {
       hd: xs_0,
       tl: xs_1
     };
-    Test_utils.ok("File \"option_repr_test.res\", line 130, characters 6-13", Belt_List.every(xs, x => x));
+    Test_utils.ok("File \"option_repr_test.res\", line 130, characters 6-13", Stdlib_List.every(xs, x => x));
   });
   Mocha.test("option equality operations", () => {
     let xs_1 = {
@@ -216,7 +216,7 @@ Mocha.describe("Option_repr_test", () => {
       hd: true,
       tl: xs_1
     };
-    Test_utils.ok("File \"option_repr_test.res\", line 149, characters 6-13", Belt_List.every(xs, x => x));
+    Test_utils.ok("File \"option_repr_test.res\", line 149, characters 6-13", Stdlib_List.every(xs, x => x));
   });
 });
 
diff --git a/tests/tests/src/option_repr_test.res b/tests/tests/src/option_repr_test.res
index 1d27812cea4..9d3cb9eb298 100644
--- a/tests/tests/src/option_repr_test.res
+++ b/tests/tests/src/option_repr_test.res
@@ -77,10 +77,10 @@ let a = f13(~x=2, ())
 
 let f12 = (x: list<_>) => Some(x)
 
-module N = Belt.List
+module N = List
 
-let length_8_id: list<int> = N.makeBy(8, x => x)
-let length_10_id: list<int> = N.makeBy(10, x => x)
+let length_8_id: list<int> = N.fromInitializer(~length=8, x => x)
+let length_10_id: list<int> = N.fromInitializer(~length=10, x => x)
 
 type xx<'a> = option<'a> =
   | None
@@ -110,7 +110,7 @@ let gtx = (a, b) => a > b && b < a
 let eqx = (a, b) => a == b && b == a
 let neqx = (a, b) => a != b && b != a
 
-let all_true = xs => Belt.List.every(xs, x => x)
+let all_true = xs => List.every(xs, x => x)
 
 describe(__MODULE__, () => {
   test("option comparison operations", () => {
diff --git a/tests/tests/src/raw_pure_test.mjs b/tests/tests/src/raw_pure_test.mjs
index 13c30aa0036..9d102167dad 100644
--- a/tests/tests/src/raw_pure_test.mjs
+++ b/tests/tests/src/raw_pure_test.mjs
@@ -4,7 +4,7 @@
 */
 // hello
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 let x0 = null;
 
@@ -22,7 +22,7 @@ function f(x) {
   return x;
 }
 
-let hh = Belt_List.length;
+let hh = Stdlib_List.length;
 
 export {
   x0,
diff --git a/tests/tests/src/raw_pure_test.res b/tests/tests/src/raw_pure_test.res
index 7f5617c6a74..4dca38755be 100644
--- a/tests/tests/src/raw_pure_test.res
+++ b/tests/tests/src/raw_pure_test.res
@@ -22,7 +22,7 @@ let x3 = %raw(`/ghoghos/`)
 `)
 
 let f = %raw("/*hello*/ 0 ")
-let hh = Belt.List.length
+let hh = List.length
 let f = x => {
   ignore(
     %raw("//eslint-disable
diff --git a/tests/tests/src/record_extension_test.mjs b/tests/tests/src/record_extension_test.mjs
index 581feb83a03..16b6161f820 100644
--- a/tests/tests/src/record_extension_test.mjs
+++ b/tests/tests/src/record_extension_test.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Int from "@rescript/runtime/lib/es6/Belt_Int.mjs";
+import * as Stdlib_Int from "@rescript/runtime/lib/es6/Stdlib_Int.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Primitive_exceptions from "@rescript/runtime/lib/es6/Primitive_exceptions.mjs";
 
@@ -13,7 +13,7 @@ let TuplePayload = /* @__PURE__ */Primitive_exceptions.create("Record_extension_
 
 function f(x) {
   if (x.RE_EXN_ID === Inline_record) {
-    let y = Belt_Int.fromString(x.y);
+    let y = Stdlib_Int.fromString(x.y);
     if (y !== undefined) {
       return x.x + y | 0;
     } else {
@@ -21,12 +21,12 @@ function f(x) {
     }
   }
   if (x.RE_EXN_ID === SinglePayload) {
-    return Belt_Int.fromString(x._1);
+    return Stdlib_Int.fromString(x._1);
   }
   if (x.RE_EXN_ID !== TuplePayload) {
     return;
   }
-  let v1 = Belt_Int.fromString(x._2);
+  let v1 = Stdlib_Int.fromString(x._2);
   if (v1 !== undefined) {
     return x._1 + v1 | 0;
   }
diff --git a/tests/tests/src/record_extension_test.res b/tests/tests/src/record_extension_test.res
index ebcd0fba29b..18a11b99222 100644
--- a/tests/tests/src/record_extension_test.res
+++ b/tests/tests/src/record_extension_test.res
@@ -9,13 +9,13 @@ type t0 += SinglePayload(string) | TuplePayload(int, string)
 let f = x =>
   switch x {
   | Inline_record({x, y}) =>
-    switch Belt.Int.fromString(y) {
+    switch Int.fromString(y) {
     | Some(y) => Some(x + y)
     | _ => None
     }
-  | SinglePayload(v) => Belt.Int.fromString(v)
+  | SinglePayload(v) => Int.fromString(v)
   | TuplePayload(v0, v1) =>
-    switch Belt.Int.fromString(v1) {
+    switch Int.fromString(v1) {
     | Some(v1) => Some(v0 + v1)
     | _ => None
     }
diff --git a/tests/tests/src/recursive_records_test.mjs b/tests/tests/src/recursive_records_test.mjs
index e9b4777c803..088596f1404 100644
--- a/tests/tests/src/recursive_records_test.mjs
+++ b/tests/tests/src/recursive_records_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
 
 let rec_cell = {};
@@ -89,9 +89,9 @@ Mocha.describe("Recursive_records_test", () => {
     Test_utils.eq("File \"recursive_records_test.res\", line 63, characters 7-14", (hd(rec_cell2$1) + hd(tl_exn(rec_cell2$1)) | 0) + hd(tl_exn(tl_exn(rec_cell2$1))) | 0, 9);
   });
   Mocha.test("recursive variant list operations", () => {
-    Test_utils.eq("File \"recursive_records_test.res\", line 69, characters 7-14", (Belt_List.headExn(rec_cell3) + Belt_List.headExn(Belt_List.tailExn(rec_cell3)) | 0) + Belt_List.headExn(Belt_List.tailExn(Belt_List.tailExn(rec_cell3))) | 0, 9);
+    Test_utils.eq("File \"recursive_records_test.res\", line 69, characters 7-14", (Stdlib_List.headExn(rec_cell3) + Stdlib_List.headExn(Stdlib_List.tailExn(rec_cell3)) | 0) + Stdlib_List.headExn(Stdlib_List.tailExn(Stdlib_List.tailExn(rec_cell3))) | 0, 9);
     let rec_cell3$1 = f3(3);
-    Test_utils.eq("File \"recursive_records_test.res\", line 71, characters 7-14", (Belt_List.headExn(rec_cell3$1) + Belt_List.headExn(Belt_List.tailExn(rec_cell3$1)) | 0) + Belt_List.headExn(Belt_List.tailExn(Belt_List.tailExn(rec_cell3$1))) | 0, 9);
+    Test_utils.eq("File \"recursive_records_test.res\", line 71, characters 7-14", (Stdlib_List.headExn(rec_cell3$1) + Stdlib_List.headExn(Stdlib_List.tailExn(rec_cell3$1)) | 0) + Stdlib_List.headExn(Stdlib_List.tailExn(Stdlib_List.tailExn(rec_cell3$1))) | 0, 9);
   });
 });
 
diff --git a/tests/tests/src/recursive_records_test.res b/tests/tests/src/recursive_records_test.res
index 9f4a7d7b135..fe70c1784b6 100644
--- a/tests/tests/src/recursive_records_test.res
+++ b/tests/tests/src/recursive_records_test.res
@@ -64,8 +64,8 @@ describe(__MODULE__, () => {
   })
 
   test("recursive variant list operations", () => {
-    let hd = Belt.List.headExn
-    let tl = Belt.List.tailExn
+    let hd = List.headExn
+    let tl = List.tailExn
     eq(__LOC__, hd(rec_cell3) + hd(tl(rec_cell3)) + hd(tl(tl(rec_cell3))), 9)
     let rec_cell3 = f3(3)
     eq(__LOC__, hd(rec_cell3) + hd(tl(rec_cell3)) + hd(tl(tl(rec_cell3))), 9)
diff --git a/tests/tests/src/set_gen.mjs b/tests/tests/src/set_gen.mjs
index 576ef8f0e8e..62e5d2de7e4 100644
--- a/tests/tests/src/set_gen.mjs
+++ b/tests/tests/src/set_gen.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_exceptions from "@rescript/runtime/lib/es6/Primitive_exceptions.mjs";
 
 function cons_enum(_s, _e) {
@@ -527,7 +527,7 @@ function of_sorted_list(l) {
       Error: new Error()
     };
   };
-  return sub(Belt_List.length(l), l)[0];
+  return sub(Stdlib_List.length(l), l)[0];
 }
 
 function of_sorted_array(l) {
diff --git a/tests/tests/src/set_gen.res b/tests/tests/src/set_gen.res
index d9c0a898f09..3701a5db8d8 100644
--- a/tests/tests/src/set_gen.res
+++ b/tests/tests/src/set_gen.res
@@ -451,7 +451,7 @@ let of_sorted_list = l => {
       }
     }
 
-  fst(sub(Belt.List.length(l), l))
+  fst(sub(List.length(l), l))
 }
 
 let of_sorted_array = l => {
@@ -459,27 +459,27 @@ let of_sorted_array = l => {
     if n == 0 {
       Empty
     } else if n == 1 {
-      let x0 = Belt.Array.getUnsafe(l, start)
+      let x0 = Array.getUnsafe(l, start)
       Node(Empty, x0, Empty, 1)
     } else if n == 2 {
-      let x0 = Belt.Array.getUnsafe(l, start)
-      let x1 = Belt.Array.getUnsafe(l, start + 1)
+      let x0 = Array.getUnsafe(l, start)
+      let x1 = Array.getUnsafe(l, start + 1)
       Node(Node(Empty, x0, Empty, 1), x1, Empty, 2)
     } else if n == 3 {
-      let x0 = Belt.Array.getUnsafe(l, start)
-      let x1 = Belt.Array.getUnsafe(l, start + 1)
-      let x2 = Belt.Array.getUnsafe(l, start + 2)
+      let x0 = Array.getUnsafe(l, start)
+      let x1 = Array.getUnsafe(l, start + 1)
+      let x2 = Array.getUnsafe(l, start + 2)
       Node(Node(Empty, x0, Empty, 1), x1, Node(Empty, x2, Empty, 1), 2)
     } else {
       let nl = n / 2
       let left = sub(start, nl, l)
       let mid = start + nl
-      let v = Belt.Array.getUnsafe(l, mid)
+      let v = Array.getUnsafe(l, mid)
       let right = sub(mid + 1, n - nl - 1, l)
       create(left, v, right)
     }
 
-  sub(0, Belt.Array.length(l), l)
+  sub(0, Array.length(l), l)
 }
 
 let is_ordered = (cmp, tree) => {
diff --git a/tests/tests/src/side_effect2.mjs b/tests/tests/src/side_effect2.mjs
index 4342186cf93..68c19570e01 100644
--- a/tests/tests/src/side_effect2.mjs
+++ b/tests/tests/src/side_effect2.mjs
@@ -1,8 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 
-let a = Belt_Array.map([1], x => x);
+let a = [1].map(x => x);
 
 export {
   a,
diff --git a/tests/tests/src/side_effect2.res b/tests/tests/src/side_effect2.res
index 6d45776b597..8a1ea82ea7f 100644
--- a/tests/tests/src/side_effect2.res
+++ b/tests/tests/src/side_effect2.res
@@ -1 +1 @@
-let a = Belt.Array.map([1], x => x)
+let a = Array.map([1], x => x)
diff --git a/tests/tests/src/splice_test.mjs b/tests/tests/src/splice_test.mjs
index 72481fe54b7..96351acc4b3 100644
--- a/tests/tests/src/splice_test.mjs
+++ b/tests/tests/src/splice_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 let Caml_splice_call = {};
 
@@ -15,7 +15,7 @@ function f00(a, b) {
 Mocha.test("splice_test_static", () => {
   let a = [];
   a.push(1, 2, 3, 4);
-  Test_utils.eq("File \"splice_test.res\", line 23, characters 5-12", a, [
+  Test_utils.eq("File \"splice_test.res\", line 22, characters 5-12", a, [
     1,
     2,
     3,
@@ -26,7 +26,7 @@ Mocha.test("splice_test_static", () => {
 function dynamic(arr) {
   let a = [];
   a.push(1, ...arr);
-  Test_utils.eq("File \"splice_test.res\", line 29, characters 5-12", a, Belt_Array.concatMany([
+  Test_utils.eq("File \"splice_test.res\", line 28, characters 5-12", a, Stdlib_Array.concatAll([
     [1],
     arr
   ]));
@@ -48,7 +48,7 @@ dynamic([
 
 Mocha.test("splice_test_newArr_static", () => {
   let a = new Array(1, 2, 3, 4);
-  Test_utils.eq("File \"splice_test.res\", line 44, characters 5-12", a, [
+  Test_utils.eq("File \"splice_test.res\", line 43, characters 5-12", a, [
     1,
     2,
     3,
@@ -58,7 +58,7 @@ Mocha.test("splice_test_newArr_static", () => {
 
 function dynamicNew(arr) {
   let a = new Array(1, 2, ...arr);
-  Test_utils.eq("File \"splice_test.res\", line 49, characters 5-12", a, Belt_Array.concatMany([
+  Test_utils.eq("File \"splice_test.res\", line 48, characters 5-12", a, Stdlib_Array.concatAll([
     [
       1,
       2
@@ -88,7 +88,7 @@ class Foo {
 
 Mocha.test("splice_test_foo_static", () => {
   let f = new Foo("a", "b", "c");
-  Test_utils.eq("File \"splice_test.res\", line 71, characters 5-12", f.names, [
+  Test_utils.eq("File \"splice_test.res\", line 70, characters 5-12", f.names, [
     "a",
     "b",
     "c"
@@ -97,7 +97,7 @@ Mocha.test("splice_test_foo_static", () => {
 
 function dynamicFoo(arr) {
   let f = new Foo(...arr);
-  Test_utils.eq("File \"splice_test.res\", line 76, characters 5-12", f.names, arr);
+  Test_utils.eq("File \"splice_test.res\", line 75, characters 5-12", f.names, arr);
 }
 
 dynamicFoo([]);
@@ -114,7 +114,7 @@ let a = [];
 
 a.push(1, 2, 3, 4);
 
-Test_utils.eq("File \"splice_test.res\", line 93, characters 7-14", a, [
+Test_utils.eq("File \"splice_test.res\", line 92, characters 7-14", a, [
   1,
   2,
   3,
@@ -124,7 +124,7 @@ Test_utils.eq("File \"splice_test.res\", line 93, characters 7-14", a, [
 function dynamic$1(arr) {
   let a = [];
   a.push(1, ...arr);
-  Test_utils.eq("File \"splice_test.res\", line 99, characters 7-14", a, Belt_Array.concatMany([
+  Test_utils.eq("File \"splice_test.res\", line 98, characters 7-14", a, Stdlib_Array.concatAll([
     [1],
     arr
   ]));
@@ -153,9 +153,9 @@ function f1(c) {
 }
 
 Mocha.describe("splice_test.res", () => {
-  Mocha.test("f1 with [2, 3]", () => Test_utils.eq("File \"splice_test.res\", line 110, characters 34-41", 3, Math.max(1, 2, 3)));
-  Mocha.test("f1 with empty", () => Test_utils.eq("File \"splice_test.res\", line 111, characters 33-40", 1, Math.max(1)));
-  Mocha.test("f1 with many values", () => Test_utils.eq("File \"splice_test.res\", line 112, characters 39-46", 5, Math.max(1, 1, 2, 3, 4, 5, 2, 3)));
+  Mocha.test("f1 with [2, 3]", () => Test_utils.eq("File \"splice_test.res\", line 109, characters 34-41", 3, Math.max(1, 2, 3)));
+  Mocha.test("f1 with empty", () => Test_utils.eq("File \"splice_test.res\", line 110, characters 33-40", 1, Math.max(1)));
+  Mocha.test("f1 with many values", () => Test_utils.eq("File \"splice_test.res\", line 111, characters 39-46", 5, Math.max(1, 1, 2, 3, 4, 5, 2, 3)));
 });
 
 export {
diff --git a/tests/tests/src/splice_test.res b/tests/tests/src/splice_test.res
index 79ec33af1d4..4f64cfe9442 100644
--- a/tests/tests/src/splice_test.res
+++ b/tests/tests/src/splice_test.res
@@ -1,6 +1,5 @@
 open Mocha
 open Test_utils
-open Belt
 
 module Caml_splice_call = {}
 @variadic @val external f: (int, array<int>) => int = "Math.max"
@@ -26,7 +25,7 @@ test("splice_test_static", () => {
 let dynamic = arr => {
   let a = []
   a->push(1, arr)
-  eq(__LOC__, a, Array.concatMany([[1], arr]))
+  eq(__LOC__, a, Array.concatAll([[1], arr]))
 }
 
 dynamic([2, 3, 4])
@@ -46,7 +45,7 @@ test("splice_test_newArr_static", () => {
 
 let dynamicNew = arr => {
   let a = newArr(1, 2, arr)
-  eq(__LOC__, a, Array.concatMany([[1, 2], arr]))
+  eq(__LOC__, a, Array.concatAll([[1, 2], arr]))
 }
 
 dynamicNew([3, 4])
@@ -96,7 +95,7 @@ module Pipe = {
   let dynamic = arr => {
     let a = []
     a->push(1, arr)
-    eq(__LOC__, a, Array.concatMany([[1], arr]))
+    eq(__LOC__, a, Array.concatAll([[1], arr]))
   }
 
   dynamic([2, 3, 4])
diff --git a/tests/tests/src/stdlib/Stdlib_IteratorTests.mjs b/tests/tests/src/stdlib/Stdlib_IteratorTests.mjs
index 8b26a7cb3e1..d32ecb0bc0c 100644
--- a/tests/tests/src/stdlib/Stdlib_IteratorTests.mjs
+++ b/tests/tests/src/stdlib/Stdlib_IteratorTests.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Test from "./Test.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Primitive_array from "@rescript/runtime/lib/es6/Primitive_array.mjs";
 import * as Stdlib_Iterator from "@rescript/runtime/lib/es6/Stdlib_Iterator.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
 import * as Stdlib_Generator from "@rescript/runtime/lib/es6/Stdlib_Generator.mjs";
@@ -571,7 +571,7 @@ let asyncOmittedDoneIterator = (({
 }));
 
 await Stdlib_AsyncIterator.forEach(asyncOmittedDoneIterator, value => {
-  asyncOmittedDoneValues.contents = Belt_Array.concatMany([
+  asyncOmittedDoneValues.contents = Primitive_array.spread([
     asyncOmittedDoneValues.contents,
     [value]
   ]);
@@ -624,7 +624,7 @@ let asyncGeneratorIterable = ((async function* () {
 })());
 
 await Stdlib_AsyncIterableIterator.forEach(asyncGeneratorIterable, value => {
-  asyncGeneratorIterableValues.contents = Belt_Array.concatMany([
+  asyncGeneratorIterableValues.contents = Primitive_array.spread([
     asyncGeneratorIterableValues.contents,
     [value]
   ]);
@@ -654,7 +654,7 @@ let asyncIterableForAwait = ((async function* () {
 })());
 
 for await (let value of asyncIterableForAwait) {
-  asyncIterableForAwaitValues.contents = Belt_Array.concatMany([
+  asyncIterableForAwaitValues.contents = Primitive_array.spread([
     asyncIterableForAwaitValues.contents,
     [value]
   ]);
@@ -696,7 +696,7 @@ loop_0: for await (let value$1 of asyncIterableForAwaitLoopControl) {
       exit = 1;
   }
   if (exit === 1) {
-    asyncIterableForAwaitLoopControlValues.contents = Belt_Array.concatMany([
+    asyncIterableForAwaitLoopControlValues.contents = Primitive_array.spread([
       asyncIterableForAwaitLoopControlValues.contents,
       [value$1]
     ]);
diff --git a/tests/tests/src/string_set.mjs b/tests/tests/src/string_set.mjs
index 97339a79da4..1aead4864ec 100644
--- a/tests/tests/src/string_set.mjs
+++ b/tests/tests/src/string_set.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Set_gen from "./set_gen.mjs";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 import * as Primitive_string from "@rescript/runtime/lib/es6/Primitive_string.mjs";
 
 function compare_elt(a, b) {
@@ -263,7 +263,7 @@ function of_list(l) {
   let x3 = match$2.hd;
   if (match$3 !== 0) {
     if (match$3.tl !== 0) {
-      return Set_gen.of_sorted_list(Belt_List.sort(l, compare_elt));
+      return Set_gen.of_sorted_list(Stdlib_List.sort(l, (a, b) => Primitive_string.compare(a, b) | 0));
     } else {
       return add(match$3.hd, add(x3, add(x2, add(x1, Set_gen.singleton(x0)))));
     }
@@ -273,7 +273,7 @@ function of_list(l) {
 }
 
 function of_array(l) {
-  return Belt_Array.reduceReverse(l, Set_gen.empty, (acc, x) => add(x, acc));
+  return Stdlib_Array.reduceRight(l, Set_gen.empty, (acc, x) => add(x, acc));
 }
 
 function invariant(t) {
diff --git a/tests/tests/src/string_set.res b/tests/tests/src/string_set.res
index 6804a07abd2..43e592a7edc 100644
--- a/tests/tests/src/string_set.res
+++ b/tests/tests/src/string_set.res
@@ -192,10 +192,10 @@ let of_list = l =>
   | list{x0, x1, x2} => add(x2, add(x1, singleton(x0)))
   | list{x0, x1, x2, x3} => add(x3, add(x2, add(x1, singleton(x0))))
   | list{x0, x1, x2, x3, x4} => add(x4, add(x3, add(x2, add(x1, singleton(x0)))))
-  | _ => of_sorted_list(l->Belt.List.sort(compare_elt))
+  | _ => of_sorted_list(l->List.sort((a, b) => compare_elt(a, b)->Int.toFloat))
   }
 
-let of_array = l => l->Belt.Array.reduceReverse(empty, (acc, x) => add(x, acc))
+let of_array = l => l->Array.reduceRight(empty, (acc, x) => add(x, acc))
 
 /* also check order */
 let invariant = t => {
diff --git a/tests/tests/src/tailcall_inline_test.mjs b/tests/tests/src/tailcall_inline_test.mjs
index 47f28fb0756..52e0888949f 100644
--- a/tests/tests/src/tailcall_inline_test.mjs
+++ b/tests/tests/src/tailcall_inline_test.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 function f() {
   let f$1 = (_acc, _n) => {
@@ -17,7 +17,7 @@ function f() {
       continue;
     };
   };
-  let v = Belt_Array.make(10, 0);
+  let v = Stdlib_Array.make(10, 0);
   for (let i = 0; i <= 9; ++i) {
     v[i] = f$1(0, i);
   }
diff --git a/tests/tests/src/tailcall_inline_test.res b/tests/tests/src/tailcall_inline_test.res
index 9c73d7ab80a..7f31d3b79ce 100644
--- a/tests/tests/src/tailcall_inline_test.res
+++ b/tests/tests/src/tailcall_inline_test.res
@@ -6,7 +6,7 @@ let f = () => {
       acc
     }
   let len = 10
-  let v = Belt.Array.make(len, 0)
+  let v = Array.make(~length=len, 0)
   for i in 0 to len - 1 {
     v[i] = f(0, i)
   }
diff --git a/tests/tests/src/test_ari.mjs b/tests/tests/src/test_ari.mjs
index 96f8e9cb852..64f2fa23b66 100644
--- a/tests/tests/src/test_ari.mjs
+++ b/tests/tests/src/test_ari.mjs
@@ -2,7 +2,7 @@
 
 import * as U from "U";
 import * as VV from "VV";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function f(x, y) {
   return x + y | 0;
@@ -41,187 +41,125 @@ function length_aux(_len, _x) {
   };
 }
 
-let length = Belt_List.length;
+let length = Stdlib_List.length;
 
-let size = Belt_List.size;
+let size = Stdlib_List.size;
 
-let head = Belt_List.head;
+let head = Stdlib_List.head;
 
-let headExn = Belt_List.headExn;
+let headExn = Stdlib_List.headExn;
 
-let headOrThrow = Belt_List.headOrThrow;
+let headOrThrow = Stdlib_List.headOrThrow;
 
-let tail = Belt_List.tail;
+let tail = Stdlib_List.tail;
 
-let tailExn = Belt_List.tailExn;
+let tailExn = Stdlib_List.tailExn;
 
-let tailOrThrow = Belt_List.tailOrThrow;
+let tailOrThrow = Stdlib_List.tailOrThrow;
 
-let add = Belt_List.add;
+let add = Stdlib_List.add;
 
-let get = Belt_List.get;
+let get = Stdlib_List.get;
 
-let getExn = Belt_List.getExn;
+let getExn = Stdlib_List.getExn;
 
-let getOrThrow = Belt_List.getOrThrow;
+let getOrThrow = Stdlib_List.getOrThrow;
 
-let make = Belt_List.make;
+let make = Stdlib_List.make;
 
-let makeByU = Belt_List.makeByU;
+let fromInitializer = Stdlib_List.fromInitializer;
 
-let makeBy = Belt_List.makeBy;
+let shuffle = Stdlib_List.shuffle;
 
-let shuffle = Belt_List.shuffle;
+let toShuffled = Stdlib_List.toShuffled;
 
-let drop = Belt_List.drop;
+let drop = Stdlib_List.drop;
 
-let take = Belt_List.take;
+let take = Stdlib_List.take;
 
-let splitAt = Belt_List.splitAt;
+let splitAt = Stdlib_List.splitAt;
 
-let concat = Belt_List.concat;
+let concat = Stdlib_List.concat;
 
-let concatMany = Belt_List.concatMany;
+let concatMany = Stdlib_List.concatMany;
 
-let reverseConcat = Belt_List.reverseConcat;
+let reverseConcat = Stdlib_List.reverseConcat;
 
-let flatten = Belt_List.flatten;
+let flat = Stdlib_List.flat;
 
-let mapU = Belt_List.mapU;
+let map = Stdlib_List.map;
 
-let map = Belt_List.map;
+let zip = Stdlib_List.zip;
 
-let zip = Belt_List.zip;
+let zipBy = Stdlib_List.zipBy;
 
-let zipByU = Belt_List.zipByU;
+let mapWithIndex = Stdlib_List.mapWithIndex;
 
-let zipBy = Belt_List.zipBy;
+let fromArray = Stdlib_List.fromArray;
 
-let mapWithIndexU = Belt_List.mapWithIndexU;
+let toArray = Stdlib_List.toArray;
 
-let mapWithIndex = Belt_List.mapWithIndex;
+let reverse = Stdlib_List.reverse;
 
-let fromArray = Belt_List.fromArray;
+let mapReverse = Stdlib_List.mapReverse;
 
-let toArray = Belt_List.toArray;
+let forEach = Stdlib_List.forEach;
 
-let reverse = Belt_List.reverse;
+let forEachWithIndex = Stdlib_List.forEachWithIndex;
 
-let mapReverseU = Belt_List.mapReverseU;
+let reduce = Stdlib_List.reduce;
 
-let mapReverse = Belt_List.mapReverse;
+let reduceWithIndex = Stdlib_List.reduceWithIndex;
 
-let forEachU = Belt_List.forEachU;
+let reduceReverse = Stdlib_List.reduceReverse;
 
-let forEach = Belt_List.forEach;
+let mapReverse2 = Stdlib_List.mapReverse2;
 
-let forEachWithIndexU = Belt_List.forEachWithIndexU;
+let forEach2 = Stdlib_List.forEach2;
 
-let forEachWithIndex = Belt_List.forEachWithIndex;
+let reduce2 = Stdlib_List.reduce2;
 
-let reduceU = Belt_List.reduceU;
+let reduceReverse2 = Stdlib_List.reduceReverse2;
 
-let reduce = Belt_List.reduce;
+let every = Stdlib_List.every;
 
-let reduceWithIndexU = Belt_List.reduceWithIndexU;
+let some = Stdlib_List.some;
 
-let reduceWithIndex = Belt_List.reduceWithIndex;
+let every2 = Stdlib_List.every2;
 
-let reduceReverseU = Belt_List.reduceReverseU;
+let some2 = Stdlib_List.some2;
 
-let reduceReverse = Belt_List.reduceReverse;
+let compareLength = Stdlib_List.compareLength;
 
-let mapReverse2U = Belt_List.mapReverse2U;
+let compare = Stdlib_List.compare;
 
-let mapReverse2 = Belt_List.mapReverse2;
+let equal = Stdlib_List.equal;
 
-let forEach2U = Belt_List.forEach2U;
+let has = Stdlib_List.has;
 
-let forEach2 = Belt_List.forEach2;
+let includes = Stdlib_List.includes;
 
-let reduce2U = Belt_List.reduce2U;
+let find = Stdlib_List.find;
 
-let reduce2 = Belt_List.reduce2;
+let filter = Stdlib_List.filter;
 
-let reduceReverse2U = Belt_List.reduceReverse2U;
+let filterWithIndex = Stdlib_List.filterWithIndex;
 
-let reduceReverse2 = Belt_List.reduceReverse2;
+let filterMap = Stdlib_List.filterMap;
 
-let everyU = Belt_List.everyU;
+let partition = Stdlib_List.partition;
 
-let every = Belt_List.every;
+let unzip = Stdlib_List.unzip;
 
-let someU = Belt_List.someU;
+let getAssoc = Stdlib_List.getAssoc;
 
-let some = Belt_List.some;
+let hasAssoc = Stdlib_List.hasAssoc;
 
-let every2U = Belt_List.every2U;
+let removeAssoc = Stdlib_List.removeAssoc;
 
-let every2 = Belt_List.every2;
+let setAssoc = Stdlib_List.setAssoc;
 
-let some2U = Belt_List.some2U;
-
-let some2 = Belt_List.some2;
-
-let cmpByLength = Belt_List.cmpByLength;
-
-let cmpU = Belt_List.cmpU;
-
-let cmp = Belt_List.cmp;
-
-let eqU = Belt_List.eqU;
-
-let eq = Belt_List.eq;
-
-let hasU = Belt_List.hasU;
-
-let has = Belt_List.has;
-
-let getByU = Belt_List.getByU;
-
-let getBy = Belt_List.getBy;
-
-let keepU = Belt_List.keepU;
-
-let keep = Belt_List.keep;
-
-let filter = Belt_List.filter;
-
-let keepWithIndexU = Belt_List.keepWithIndexU;
-
-let keepWithIndex = Belt_List.keepWithIndex;
-
-let filterWithIndex = Belt_List.filterWithIndex;
-
-let keepMapU = Belt_List.keepMapU;
-
-let keepMap = Belt_List.keepMap;
-
-let partitionU = Belt_List.partitionU;
-
-let partition = Belt_List.partition;
-
-let unzip = Belt_List.unzip;
-
-let getAssocU = Belt_List.getAssocU;
-
-let getAssoc = Belt_List.getAssoc;
-
-let hasAssocU = Belt_List.hasAssocU;
-
-let hasAssoc = Belt_List.hasAssoc;
-
-let removeAssocU = Belt_List.removeAssocU;
-
-let removeAssoc = Belt_List.removeAssoc;
-
-let setAssocU = Belt_List.setAssocU;
-
-let setAssoc = Belt_List.setAssoc;
-
-let sortU = Belt_List.sortU;
-
-let sort = Belt_List.sort;
+let sort = Stdlib_List.sort;
 
 export {
   f,
@@ -245,83 +183,52 @@ export {
   getExn,
   getOrThrow,
   make,
-  makeByU,
-  makeBy,
+  fromInitializer,
   shuffle,
+  toShuffled,
   drop,
   take,
   splitAt,
   concat,
   concatMany,
   reverseConcat,
-  flatten,
-  mapU,
+  flat,
   map,
   zip,
-  zipByU,
   zipBy,
-  mapWithIndexU,
   mapWithIndex,
   fromArray,
   toArray,
   reverse,
-  mapReverseU,
   mapReverse,
-  forEachU,
   forEach,
-  forEachWithIndexU,
   forEachWithIndex,
-  reduceU,
   reduce,
-  reduceWithIndexU,
   reduceWithIndex,
-  reduceReverseU,
   reduceReverse,
-  mapReverse2U,
   mapReverse2,
-  forEach2U,
   forEach2,
-  reduce2U,
   reduce2,
-  reduceReverse2U,
   reduceReverse2,
-  everyU,
   every,
-  someU,
   some,
-  every2U,
   every2,
-  some2U,
   some2,
-  cmpByLength,
-  cmpU,
-  cmp,
-  eqU,
-  eq,
-  hasU,
+  compareLength,
+  compare,
+  equal,
   has,
-  getByU,
-  getBy,
-  keepU,
-  keep,
+  includes,
+  find,
   filter,
-  keepWithIndexU,
-  keepWithIndex,
   filterWithIndex,
-  keepMapU,
-  keepMap,
-  partitionU,
+  filterMap,
   partition,
   unzip,
-  getAssocU,
   getAssoc,
-  hasAssocU,
   hasAssoc,
-  removeAssocU,
   removeAssoc,
-  setAssocU,
   setAssoc,
-  sortU,
   sort,
 }
 /* fff Not a pure module */
diff --git a/tests/tests/src/test_ari.res b/tests/tests/src/test_ari.res
index 8d970ef3019..6fbf8ef5410 100644
--- a/tests/tests/src/test_ari.res
+++ b/tests/tests/src/test_ari.res
@@ -31,4 +31,4 @@ let rec length_aux = (len, x) =>
   | list{a, ...l} => length_aux(len + 1, l)
   }
 
-include Belt.List
+include List
diff --git a/tests/tests/src/test_array_append.mjs b/tests/tests/src/test_array_append.mjs
index 7e8bfc7aec8..df0687ae042 100644
--- a/tests/tests/src/test_array_append.mjs
+++ b/tests/tests/src/test_array_append.mjs
@@ -1,11 +1,10 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 
-let const_v = Belt_Array.concat([
+let const_v = [
   1,
   2
-], [3]);
+].concat([3]);
 
 export {
   const_v,
diff --git a/tests/tests/src/test_array_append.res b/tests/tests/src/test_array_append.res
index e48887f99a9..b37df5118e0 100644
--- a/tests/tests/src/test_array_append.res
+++ b/tests/tests/src/test_array_append.res
@@ -1 +1 @@
-let const_v = Belt.Array.concat([1, 2], [3])
+let const_v = Array.concat([1, 2], [3])
diff --git a/tests/tests/src/test_bool_equal.res b/tests/tests/src/test_bool_equal.res
index 304644a39ae..5264d2073f7 100644
--- a/tests/tests/src/test_bool_equal.res
+++ b/tests/tests/src/test_bool_equal.res
@@ -70,14 +70,14 @@ let f6 = x =>
   }
 
 let f7 = x =>
-  if Belt.Array.length(x) > 0 {
+  if Array.length(x) > 0 {
     1
   } else {
     2
   }
 
 let f8 = x =>
-  if Belt.Array.length(x) >= 0 {
+  if Array.length(x) >= 0 {
     1
   } else {
     2
diff --git a/tests/tests/src/test_closure.mjs b/tests/tests/src/test_closure.mjs
index 09628d2cd34..eefaa61d4f2 100644
--- a/tests/tests/src/test_closure.mjs
+++ b/tests/tests/src/test_closure.mjs
@@ -1,13 +1,13 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 let v = {
   contents: 0
 };
 
 function f() {
-  let arr = Belt_Array.make(10, param => {});
+  let arr = Stdlib_Array.make(10, param => {});
   for (let i = 0; i <= 9; ++i) {
     arr[i] = param => {
       v.contents = v.contents + i | 0;
@@ -18,7 +18,7 @@ function f() {
 
 let u = f();
 
-Belt_Array.forEach(u, x => x());
+u.forEach(x => x());
 
 if (v.contents !== 45) {
   throw {
diff --git a/tests/tests/src/test_closure.res b/tests/tests/src/test_closure.res
index 240102d95eb..7976bc34028 100644
--- a/tests/tests/src/test_closure.res
+++ b/tests/tests/src/test_closure.res
@@ -39,7 +39,7 @@ This means inline is tricky in javascript, here we try to inline [_loop]?
  */
 let f = () => {
   let n = 10
-  let arr = Belt.Array.make(10, _ => ())
+  let arr = Array.make(~length=10, _ => ())
   for i in 0 to n - 1 {
     arr[i] = _ => v := v.contents + i
   }
@@ -48,6 +48,6 @@ let f = () => {
 
 let () = {
   let u = f()
-  u->Belt.Array.forEach(x => x())
+  u->Array.forEach(x => x())
   assert(v.contents == 45)
 }
diff --git a/tests/tests/src/test_cps.mjs b/tests/tests/src/test_cps.mjs
index cfbf7c9bfcf..877ee495e3a 100644
--- a/tests/tests/src/test_cps.mjs
+++ b/tests/tests/src/test_cps.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 function f(_n, _acc) {
   while (true) {
@@ -19,7 +19,7 @@ function f(_n, _acc) {
 }
 
 function test_closure() {
-  let arr = Belt_Array.make(6, x => x);
+  let arr = Stdlib_Array.make(6, x => x);
   for (let i = 0; i <= 6; ++i) {
     arr[i] = param => i;
   }
diff --git a/tests/tests/src/test_cps.res b/tests/tests/src/test_cps.res
index 5f0dc482709..0ad655c14bc 100644
--- a/tests/tests/src/test_cps.res
+++ b/tests/tests/src/test_cps.res
@@ -90,7 +90,7 @@ let rec f = (n, acc) =>
  */
 let test_closure = () => {
   let n = 6
-  let arr = Belt.Array.make(n, x => x)
+  let arr = Array.make(~length=n, x => x)
   for i in 0 to n {
     arr[i] = _ => i
   }
diff --git a/tests/tests/src/test_demo.mjs b/tests/tests/src/test_demo.mjs
index e68b0c11ec1..948ecd410a1 100644
--- a/tests/tests/src/test_demo.mjs
+++ b/tests/tests/src/test_demo.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function fib(x) {
   if (x !== 2 && x !== 1) {
@@ -63,7 +63,7 @@ function v(extra) {
 
 let nil = "Nil";
 
-let len = Belt_List.length;
+let len = Stdlib_List.length;
 
 export {
   fib,
diff --git a/tests/tests/src/test_demo.res b/tests/tests/src/test_demo.res
index 2783d1a94e0..5da073c69a8 100644
--- a/tests/tests/src/test_demo.res
+++ b/tests/tests/src/test_demo.res
@@ -26,7 +26,7 @@ let sum = n => {
   v.contents
 }
 
-let len = Belt.List.length
+let len = List.length
 
 let f = (g, x) => {
   let u = switch g(x) {
diff --git a/tests/tests/src/test_for_loop.mjs b/tests/tests/src/test_for_loop.mjs
index ee897631600..4ec5550047d 100644
--- a/tests/tests/src/test_for_loop.mjs
+++ b/tests/tests/src/test_for_loop.mjs
@@ -1,6 +1,5 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 
 function for_(x) {
   for (let i = 0, i_finish = (console.log("hi"), x.length); i <= i_finish; ++i) {
@@ -18,14 +17,14 @@ function for_3(x) {
   let v = {
     contents: 0
   };
-  let arr = Belt_Array.map(x, param => (() => {}));
+  let arr = x.map(param => (() => {}));
   for (let i = 0, i_finish = x.length; i <= i_finish; ++i) {
     let j = (i << 1);
     arr[i] = () => {
       v.contents = v.contents + j | 0;
     };
   }
-  Belt_Array.forEach(arr, x => x());
+  arr.forEach(x => x());
   return v.contents;
 }
 
@@ -33,7 +32,7 @@ function for_4(x) {
   let v = {
     contents: 0
   };
-  let arr = Belt_Array.map(x, param => (() => {}));
+  let arr = x.map(param => (() => {}));
   for (let i = 0, i_finish = x.length; i <= i_finish; ++i) {
     let j = (i << 1);
     let k = (j << 1);
@@ -41,7 +40,7 @@ function for_4(x) {
       v.contents = v.contents + k | 0;
     };
   }
-  Belt_Array.forEach(arr, x => x());
+  arr.forEach(x => x());
   return v.contents;
 }
 
@@ -49,14 +48,14 @@ function for_5(x, u) {
   let v = {
     contents: 0
   };
-  let arr = Belt_Array.map(x, param => (() => {}));
+  let arr = x.map(param => (() => {}));
   for (let i = 0, i_finish = x.length; i <= i_finish; ++i) {
     let k = (u << 1) * u | 0;
     arr[i] = () => {
       v.contents = v.contents + k | 0;
     };
   }
-  Belt_Array.forEach(arr, x => x());
+  arr.forEach(x => x());
   return v.contents;
 }
 
@@ -64,7 +63,7 @@ function for_6(x, u) {
   let v = {
     contents: 0
   };
-  let arr = Belt_Array.map(x, param => (() => {}));
+  let arr = x.map(param => (() => {}));
   let v4 = {
     contents: 0
   };
@@ -86,7 +85,7 @@ function for_6(x, u) {
       };
     }
   }
-  Belt_Array.forEach(arr, x => x());
+  arr.forEach(x => x());
   return v.contents;
 }
 
diff --git a/tests/tests/src/test_for_loop.res b/tests/tests/src/test_for_loop.res
index 7f17eada1f5..a30681c48f6 100644
--- a/tests/tests/src/test_for_loop.res
+++ b/tests/tests/src/test_for_loop.res
@@ -2,54 +2,54 @@ let for_ = x =>
   for i in 0 to {
     Console.log("hi")
     ignore(3)
-    Belt.Array.length(x)
+    Array.length(x)
   } {
     Console.log(x[i])
   }
 
 let for_2 = x =>
-  for i in 0 to Belt.Array.length(x) {
+  for i in 0 to Array.length(x) {
     Console.log(x[i])
   }
 
 let for_3 = x => {
   let v = ref(0)
-  let arr = x->Belt.Array.map(_ => _ => ())
-  for i in 0 to Belt.Array.length(x) {
+  let arr = x->Array.map(_ => _ => ())
+  for i in 0 to Array.length(x) {
     let j = i * 2
     arr[i] = _ => v := v.contents + j
   }
-  arr->Belt.Array.forEach(x => x())
+  arr->Array.forEach(x => x())
   v.contents
 }
 
 let for_4 = x => {
   let v = ref(0)
-  let arr = x->Belt.Array.map(_ => _ => ())
-  for i in 0 to Belt.Array.length(x) {
+  let arr = x->Array.map(_ => _ => ())
+  for i in 0 to Array.length(x) {
     let j = i * 2
     let k = 2 * j
     arr[i] = _ => v := v.contents + k
   }
-  arr->Belt.Array.forEach(x => x())
+  arr->Array.forEach(x => x())
   v.contents
 }
 
 let for_5 = (x, u) => {
   let v = ref(0)
-  let arr = x->Belt.Array.map(_ => _ => ())
-  for i in 0 to Belt.Array.length(x) {
+  let arr = x->Array.map(_ => _ => ())
+  for i in 0 to Array.length(x) {
     let _j = i * 2
     let k = 2 * u * u
     arr[i] = _ => v := v.contents + k
   }
-  arr->Belt.Array.forEach(x => x())
+  arr->Array.forEach(x => x())
   v.contents
 }
 
 let for_6 = (x, u) => {
   let v = ref(0)
-  let arr = x->Belt.Array.map(_ => _ => ())
+  let arr = x->Array.map(_ => _ => ())
   let v4 = ref(0)
   let v5 = ref(0)
   incr(v4)
@@ -57,7 +57,7 @@ let for_6 = (x, u) => {
     incr(v5)
     let v2 = ref(0)
     let v3 = u
-    for i in 0 to Belt.Array.length(x) {
+    for i in 0 to Array.length(x) {
       let _j = i * 2
       let k = 2 * u * u
       let h = 2 * v5.contents
@@ -65,6 +65,6 @@ let for_6 = (x, u) => {
       arr[i] = _ => v := v.contents + k + v2.contents + v3 + v4.contents + v5.contents + h
     }
   }
-  arr->Belt.Array.forEach(x => x())
+  arr->Array.forEach(x => x())
   v.contents
 }
diff --git a/tests/tests/src/test_for_of.mjs b/tests/tests/src/test_for_of.mjs
index 6a112759f42..f9707126aff 100644
--- a/tests/tests/src/test_for_of.mjs
+++ b/tests/tests/src/test_for_of.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Mocha from "mocha";
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
+import * as Primitive_array from "@rescript/runtime/lib/es6/Primitive_array.mjs";
 
 function firstLargeOpenOrder(orders) {
   let matchId;
@@ -93,7 +93,7 @@ Mocha.describe("Test_for_of", () => {
         case 3 :
           break loop_0;
         default:
-          seen = Belt_Array.concatMany([
+          seen = Primitive_array.spread([
             seen,
             [x]
           ]);
diff --git a/tests/tests/src/test_functor_dead_code.mjs b/tests/tests/src/test_functor_dead_code.mjs
index fb93d4be3f6..b31d05f067f 100644
--- a/tests/tests/src/test_functor_dead_code.mjs
+++ b/tests/tests/src/test_functor_dead_code.mjs
@@ -1,8 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_MapString from "@rescript/runtime/lib/es6/Belt_MapString.mjs";
+import * as Stdlib_Map from "@rescript/runtime/lib/es6/Stdlib_Map.mjs";
 
-let v = Belt_MapString.isEmpty(undefined);
+let v = Stdlib_Map.isEmpty(new Map());
 
 export {
   v,
diff --git a/tests/tests/src/test_functor_dead_code.res b/tests/tests/src/test_functor_dead_code.res
index 70ccee01c5b..22432c9a52d 100644
--- a/tests/tests/src/test_functor_dead_code.res
+++ b/tests/tests/src/test_functor_dead_code.res
@@ -1,7 +1,7 @@
 include (
   {
-    module M = Belt.Map.String
-    let v = M.isEmpty(M.empty)
+    module M = Map
+    let v = M.isEmpty(M.make())
   }: {
     let v: bool
   }
diff --git a/tests/tests/src/test_google_closure.mjs b/tests/tests/src/test_google_closure.mjs
index 4f25dd724fb..bbe794b0526 100644
--- a/tests/tests/src/test_google_closure.mjs
+++ b/tests/tests/src/test_google_closure.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 function f(a, b, param) {
   return a + b | 0;
@@ -18,7 +18,7 @@ function f3(extra) {
 
 let b = f3(2);
 
-let arr = Belt_Array.init(2, param => 0);
+let arr = Stdlib_Array.fromInitializer(2, param => 0);
 
 for (let i = 0; i <= 1; ++i) {
   let f3$1 = extra => i + 1 | 0;
diff --git a/tests/tests/src/test_google_closure.res b/tests/tests/src/test_google_closure.res
index 3884927cdd4..ad4063412e2 100644
--- a/tests/tests/src/test_google_closure.res
+++ b/tests/tests/src/test_google_closure.res
@@ -9,7 +9,7 @@ let (a, b, c) = (
     f3(2)
   },
   {
-    let arr = Belt.Array.init(2, _ => 0)
+    let arr = Array.fromInitializer(~length=2, _ => 0)
     for i in 0 to 1 {
       let f3 = f2(i)
       arr[i] = f3(2)
diff --git a/tests/tests/src/test_include.mjs b/tests/tests/src/test_include.mjs
index a90af9a603b..54748ab8254 100644
--- a/tests/tests/src/test_include.mjs
+++ b/tests/tests/src/test_include.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Test_order from "./test_order.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function Make(U) {
   return {
@@ -15,7 +15,7 @@ let U = {
 
 let N;
 
-let v = Belt_List.length;
+let v = Stdlib_List.length;
 
 let N0;
 
@@ -31,187 +31,125 @@ let N5;
 
 let N6;
 
-let length = Belt_List.length;
+let length = Stdlib_List.length;
 
-let size = Belt_List.size;
+let size = Stdlib_List.size;
 
-let head = Belt_List.head;
+let head = Stdlib_List.head;
 
-let headExn = Belt_List.headExn;
+let headExn = Stdlib_List.headExn;
 
-let headOrThrow = Belt_List.headOrThrow;
+let headOrThrow = Stdlib_List.headOrThrow;
 
-let tail = Belt_List.tail;
+let tail = Stdlib_List.tail;
 
-let tailExn = Belt_List.tailExn;
+let tailExn = Stdlib_List.tailExn;
 
-let tailOrThrow = Belt_List.tailOrThrow;
+let tailOrThrow = Stdlib_List.tailOrThrow;
 
-let add = Belt_List.add;
+let add = Stdlib_List.add;
 
-let get = Belt_List.get;
+let get = Stdlib_List.get;
 
-let getExn = Belt_List.getExn;
+let getExn = Stdlib_List.getExn;
 
-let getOrThrow = Belt_List.getOrThrow;
+let getOrThrow = Stdlib_List.getOrThrow;
 
-let make = Belt_List.make;
+let make = Stdlib_List.make;
 
-let makeByU = Belt_List.makeByU;
+let fromInitializer = Stdlib_List.fromInitializer;
 
-let makeBy = Belt_List.makeBy;
+let shuffle = Stdlib_List.shuffle;
 
-let shuffle = Belt_List.shuffle;
+let toShuffled = Stdlib_List.toShuffled;
 
-let drop = Belt_List.drop;
+let drop = Stdlib_List.drop;
 
-let take = Belt_List.take;
+let take = Stdlib_List.take;
 
-let splitAt = Belt_List.splitAt;
+let splitAt = Stdlib_List.splitAt;
 
-let concat = Belt_List.concat;
+let concat = Stdlib_List.concat;
 
-let concatMany = Belt_List.concatMany;
+let concatMany = Stdlib_List.concatMany;
 
-let reverseConcat = Belt_List.reverseConcat;
+let reverseConcat = Stdlib_List.reverseConcat;
 
-let flatten = Belt_List.flatten;
+let flat = Stdlib_List.flat;
 
-let mapU = Belt_List.mapU;
+let map = Stdlib_List.map;
 
-let map = Belt_List.map;
+let zip = Stdlib_List.zip;
 
-let zip = Belt_List.zip;
+let zipBy = Stdlib_List.zipBy;
 
-let zipByU = Belt_List.zipByU;
+let mapWithIndex = Stdlib_List.mapWithIndex;
 
-let zipBy = Belt_List.zipBy;
+let fromArray = Stdlib_List.fromArray;
 
-let mapWithIndexU = Belt_List.mapWithIndexU;
+let toArray = Stdlib_List.toArray;
 
-let mapWithIndex = Belt_List.mapWithIndex;
+let reverse = Stdlib_List.reverse;
 
-let fromArray = Belt_List.fromArray;
+let mapReverse = Stdlib_List.mapReverse;
 
-let toArray = Belt_List.toArray;
+let forEach = Stdlib_List.forEach;
 
-let reverse = Belt_List.reverse;
+let forEachWithIndex = Stdlib_List.forEachWithIndex;
 
-let mapReverseU = Belt_List.mapReverseU;
+let reduce = Stdlib_List.reduce;
 
-let mapReverse = Belt_List.mapReverse;
+let reduceWithIndex = Stdlib_List.reduceWithIndex;
 
-let forEachU = Belt_List.forEachU;
+let reduceReverse = Stdlib_List.reduceReverse;
 
-let forEach = Belt_List.forEach;
+let mapReverse2 = Stdlib_List.mapReverse2;
 
-let forEachWithIndexU = Belt_List.forEachWithIndexU;
+let forEach2 = Stdlib_List.forEach2;
 
-let forEachWithIndex = Belt_List.forEachWithIndex;
+let reduce2 = Stdlib_List.reduce2;
 
-let reduceU = Belt_List.reduceU;
+let reduceReverse2 = Stdlib_List.reduceReverse2;
 
-let reduce = Belt_List.reduce;
+let every = Stdlib_List.every;
 
-let reduceWithIndexU = Belt_List.reduceWithIndexU;
+let some = Stdlib_List.some;
 
-let reduceWithIndex = Belt_List.reduceWithIndex;
+let every2 = Stdlib_List.every2;
 
-let reduceReverseU = Belt_List.reduceReverseU;
+let some2 = Stdlib_List.some2;
 
-let reduceReverse = Belt_List.reduceReverse;
+let compareLength = Stdlib_List.compareLength;
 
-let mapReverse2U = Belt_List.mapReverse2U;
+let compare = Stdlib_List.compare;
 
-let mapReverse2 = Belt_List.mapReverse2;
+let equal = Stdlib_List.equal;
 
-let forEach2U = Belt_List.forEach2U;
+let has = Stdlib_List.has;
 
-let forEach2 = Belt_List.forEach2;
+let includes = Stdlib_List.includes;
 
-let reduce2U = Belt_List.reduce2U;
+let find = Stdlib_List.find;
 
-let reduce2 = Belt_List.reduce2;
+let filter = Stdlib_List.filter;
 
-let reduceReverse2U = Belt_List.reduceReverse2U;
+let filterWithIndex = Stdlib_List.filterWithIndex;
 
-let reduceReverse2 = Belt_List.reduceReverse2;
+let filterMap = Stdlib_List.filterMap;
 
-let everyU = Belt_List.everyU;
+let partition = Stdlib_List.partition;
 
-let every = Belt_List.every;
+let unzip = Stdlib_List.unzip;
 
-let someU = Belt_List.someU;
+let getAssoc = Stdlib_List.getAssoc;
 
-let some = Belt_List.some;
+let hasAssoc = Stdlib_List.hasAssoc;
 
-let every2U = Belt_List.every2U;
+let removeAssoc = Stdlib_List.removeAssoc;
 
-let every2 = Belt_List.every2;
+let setAssoc = Stdlib_List.setAssoc;
 
-let some2U = Belt_List.some2U;
-
-let some2 = Belt_List.some2;
-
-let cmpByLength = Belt_List.cmpByLength;
-
-let cmpU = Belt_List.cmpU;
-
-let cmp = Belt_List.cmp;
-
-let eqU = Belt_List.eqU;
-
-let eq = Belt_List.eq;
-
-let hasU = Belt_List.hasU;
-
-let has = Belt_List.has;
-
-let getByU = Belt_List.getByU;
-
-let getBy = Belt_List.getBy;
-
-let keepU = Belt_List.keepU;
-
-let keep = Belt_List.keep;
-
-let filter = Belt_List.filter;
-
-let keepWithIndexU = Belt_List.keepWithIndexU;
-
-let keepWithIndex = Belt_List.keepWithIndex;
-
-let filterWithIndex = Belt_List.filterWithIndex;
-
-let keepMapU = Belt_List.keepMapU;
-
-let keepMap = Belt_List.keepMap;
-
-let partitionU = Belt_List.partitionU;
-
-let partition = Belt_List.partition;
-
-let unzip = Belt_List.unzip;
-
-let getAssocU = Belt_List.getAssocU;
-
-let getAssoc = Belt_List.getAssoc;
-
-let hasAssocU = Belt_List.hasAssocU;
-
-let hasAssoc = Belt_List.hasAssoc;
-
-let removeAssocU = Belt_List.removeAssocU;
-
-let removeAssoc = Belt_List.removeAssoc;
-
-let setAssocU = Belt_List.setAssocU;
-
-let setAssoc = Belt_List.setAssoc;
-
-let sortU = Belt_List.sortU;
-
-let sort = Belt_List.sort;
+let sort = Stdlib_List.sort;
 
 export {
   N,
@@ -238,83 +176,52 @@ export {
   getExn,
   getOrThrow,
   make,
-  makeByU,
-  makeBy,
+  fromInitializer,
   shuffle,
+  toShuffled,
   drop,
   take,
   splitAt,
   concat,
   concatMany,
   reverseConcat,
-  flatten,
-  mapU,
+  flat,
   map,
   zip,
-  zipByU,
   zipBy,
-  mapWithIndexU,
   mapWithIndex,
   fromArray,
   toArray,
   reverse,
-  mapReverseU,
   mapReverse,
-  forEachU,
   forEach,
-  forEachWithIndexU,
   forEachWithIndex,
-  reduceU,
   reduce,
-  reduceWithIndexU,
   reduceWithIndex,
-  reduceReverseU,
   reduceReverse,
-  mapReverse2U,
   mapReverse2,
-  forEach2U,
   forEach2,
-  reduce2U,
   reduce2,
-  reduceReverse2U,
   reduceReverse2,
-  everyU,
   every,
-  someU,
   some,
-  every2U,
   every2,
-  some2U,
   some2,
-  cmpByLength,
-  cmpU,
-  cmp,
-  eqU,
-  eq,
-  hasU,
+  compareLength,
+  compare,
+  equal,
   has,
-  getByU,
-  getBy,
-  keepU,
-  keep,
+  includes,
+  find,
   filter,
-  keepWithIndexU,
-  keepWithIndex,
   filterWithIndex,
-  keepMapU,
-  keepMap,
-  partitionU,
+  filterMap,
   partition,
   unzip,
-  getAssocU,
   getAssoc,
-  hasAssocU,
   hasAssoc,
-  removeAssocU,
   removeAssoc,
-  setAssocU,
   setAssoc,
-  sortU,
   sort,
 }
 /* No side effect */
diff --git a/tests/tests/src/test_include.res b/tests/tests/src/test_include.res
index 632975fee3b..3bdef8ee995 100644
--- a/tests/tests/src/test_include.res
+++ b/tests/tests/src/test_include.res
@@ -1,6 +1,4 @@
-open Belt
-
-module N = Belt.List
+module N = List
 let v = N.length
 
 module type OrderedType = {
diff --git a/tests/tests/src/test_list.mjs b/tests/tests/src/test_list.mjs
index 056142a0502..f0ebcad40e9 100644
--- a/tests/tests/src/test_list.mjs
+++ b/tests/tests/src/test_list.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function length_aux(_len, _x) {
   while (true) {
@@ -1407,7 +1407,7 @@ function isEmpty2(x) {
   return x === /* [] */0;
 }
 
-let u = Belt_List.length;
+let u = Stdlib_List.length;
 
 let append = Pervasives.$at;
 
diff --git a/tests/tests/src/test_list.res b/tests/tests/src/test_list.res
index 8de56dbec6b..47adfae7cc4 100644
--- a/tests/tests/src/test_list.res
+++ b/tests/tests/src/test_list.res
@@ -13,7 +13,7 @@
 
 /* List operations */
 
-let u = Belt.List.length
+let u = List.length
 let rec length_aux = (len, x) =>
   switch x {
   | list{} => len
diff --git a/tests/tests/src/test_pervasive.mjs b/tests/tests/src/test_pervasive.mjs
index f0f026c6c01..0014f94443b 100644
--- a/tests/tests/src/test_pervasive.mjs
+++ b/tests/tests/src/test_pervasive.mjs
@@ -1,100 +1,68 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 let Pervasives$1 = {
-  length: Belt_List.length,
-  size: Belt_List.size,
-  head: Belt_List.head,
-  headExn: Belt_List.headExn,
-  headOrThrow: Belt_List.headOrThrow,
-  tail: Belt_List.tail,
-  tailExn: Belt_List.tailExn,
-  tailOrThrow: Belt_List.tailOrThrow,
-  add: Belt_List.add,
-  get: Belt_List.get,
-  getExn: Belt_List.getExn,
-  getOrThrow: Belt_List.getOrThrow,
-  make: Belt_List.make,
-  makeByU: Belt_List.makeByU,
-  makeBy: Belt_List.makeBy,
-  shuffle: Belt_List.shuffle,
-  drop: Belt_List.drop,
-  take: Belt_List.take,
-  splitAt: Belt_List.splitAt,
-  concat: Belt_List.concat,
-  concatMany: Belt_List.concatMany,
-  reverseConcat: Belt_List.reverseConcat,
-  flatten: Belt_List.flatten,
-  mapU: Belt_List.mapU,
-  map: Belt_List.map,
-  zip: Belt_List.zip,
-  zipByU: Belt_List.zipByU,
-  zipBy: Belt_List.zipBy,
-  mapWithIndexU: Belt_List.mapWithIndexU,
-  mapWithIndex: Belt_List.mapWithIndex,
-  fromArray: Belt_List.fromArray,
-  toArray: Belt_List.toArray,
-  reverse: Belt_List.reverse,
-  mapReverseU: Belt_List.mapReverseU,
-  mapReverse: Belt_List.mapReverse,
-  forEachU: Belt_List.forEachU,
-  forEach: Belt_List.forEach,
-  forEachWithIndexU: Belt_List.forEachWithIndexU,
-  forEachWithIndex: Belt_List.forEachWithIndex,
-  reduceU: Belt_List.reduceU,
-  reduce: Belt_List.reduce,
-  reduceWithIndexU: Belt_List.reduceWithIndexU,
-  reduceWithIndex: Belt_List.reduceWithIndex,
-  reduceReverseU: Belt_List.reduceReverseU,
-  reduceReverse: Belt_List.reduceReverse,
-  mapReverse2U: Belt_List.mapReverse2U,
-  mapReverse2: Belt_List.mapReverse2,
-  forEach2U: Belt_List.forEach2U,
-  forEach2: Belt_List.forEach2,
-  reduce2U: Belt_List.reduce2U,
-  reduce2: Belt_List.reduce2,
-  reduceReverse2U: Belt_List.reduceReverse2U,
-  reduceReverse2: Belt_List.reduceReverse2,
-  everyU: Belt_List.everyU,
-  every: Belt_List.every,
-  someU: Belt_List.someU,
-  some: Belt_List.some,
-  every2U: Belt_List.every2U,
-  every2: Belt_List.every2,
-  some2U: Belt_List.some2U,
-  some2: Belt_List.some2,
-  cmpByLength: Belt_List.cmpByLength,
-  cmpU: Belt_List.cmpU,
-  cmp: Belt_List.cmp,
-  eqU: Belt_List.eqU,
-  eq: Belt_List.eq,
-  hasU: Belt_List.hasU,
-  has: Belt_List.has,
-  getByU: Belt_List.getByU,
-  getBy: Belt_List.getBy,
-  keepU: Belt_List.keepU,
-  keep: Belt_List.keep,
-  filter: Belt_List.filter,
-  keepWithIndexU: Belt_List.keepWithIndexU,
-  keepWithIndex: Belt_List.keepWithIndex,
-  filterWithIndex: Belt_List.filterWithIndex,
-  keepMapU: Belt_List.keepMapU,
-  keepMap: Belt_List.keepMap,
-  partitionU: Belt_List.partitionU,
-  partition: Belt_List.partition,
-  unzip: Belt_List.unzip,
-  getAssocU: Belt_List.getAssocU,
-  getAssoc: Belt_List.getAssoc,
-  hasAssocU: Belt_List.hasAssocU,
-  hasAssoc: Belt_List.hasAssoc,
-  removeAssocU: Belt_List.removeAssocU,
-  removeAssoc: Belt_List.removeAssoc,
-  setAssocU: Belt_List.setAssocU,
-  setAssoc: Belt_List.setAssoc,
-  sortU: Belt_List.sortU,
-  sort: Belt_List.sort,
+  length: Stdlib_List.length,
+  size: Stdlib_List.size,
+  head: Stdlib_List.head,
+  headExn: Stdlib_List.headExn,
+  headOrThrow: Stdlib_List.headOrThrow,
+  tail: Stdlib_List.tail,
+  tailExn: Stdlib_List.tailExn,
+  tailOrThrow: Stdlib_List.tailOrThrow,
+  add: Stdlib_List.add,
+  get: Stdlib_List.get,
+  getExn: Stdlib_List.getExn,
+  getOrThrow: Stdlib_List.getOrThrow,
+  make: Stdlib_List.make,
+  fromInitializer: Stdlib_List.fromInitializer,
+  shuffle: Stdlib_List.shuffle,
+  toShuffled: Stdlib_List.toShuffled,
+  drop: Stdlib_List.drop,
+  take: Stdlib_List.take,
+  splitAt: Stdlib_List.splitAt,
+  concat: Stdlib_List.concat,
+  concatMany: Stdlib_List.concatMany,
+  reverseConcat: Stdlib_List.reverseConcat,
+  flat: Stdlib_List.flat,
+  map: Stdlib_List.map,
+  zip: Stdlib_List.zip,
+  zipBy: Stdlib_List.zipBy,
+  mapWithIndex: Stdlib_List.mapWithIndex,
+  fromArray: Stdlib_List.fromArray,
+  toArray: Stdlib_List.toArray,
+  reverse: Stdlib_List.reverse,
+  mapReverse: Stdlib_List.mapReverse,
+  forEach: Stdlib_List.forEach,
+  forEachWithIndex: Stdlib_List.forEachWithIndex,
+  reduce: Stdlib_List.reduce,
+  reduceWithIndex: Stdlib_List.reduceWithIndex,
+  reduceReverse: Stdlib_List.reduceReverse,
+  mapReverse2: Stdlib_List.mapReverse2,
+  forEach2: Stdlib_List.forEach2,
+  reduce2: Stdlib_List.reduce2,
+  reduceReverse2: Stdlib_List.reduceReverse2,
+  every: Stdlib_List.every,
+  some: Stdlib_List.some,
+  every2: Stdlib_List.every2,
+  some2: Stdlib_List.some2,
+  compareLength: Stdlib_List.compareLength,
+  equal: Stdlib_List.equal,
+  has: Stdlib_List.has,
+  includes: Stdlib_List.includes,
+  find: Stdlib_List.find,
+  filter: Stdlib_List.filter,
+  filterWithIndex: Stdlib_List.filterWithIndex,
+  filterMap: Stdlib_List.filterMap,
+  partition: Stdlib_List.partition,
+  unzip: Stdlib_List.unzip,
+  getAssoc: Stdlib_List.getAssoc,
+  hasAssoc: Stdlib_List.hasAssoc,
+  removeAssoc: Stdlib_List.removeAssoc,
+  setAssoc: Stdlib_List.setAssoc,
+  sort: Stdlib_List.sort,
   failwith: Pervasives.failwith,
   invalid_arg: Pervasives.invalid_arg,
   Exit: Pervasives.Exit,
diff --git a/tests/tests/src/test_pervasive.res b/tests/tests/src/test_pervasive.res
index f280901a486..7463c6d4267 100644
--- a/tests/tests/src/test_pervasive.res
+++ b/tests/tests/src/test_pervasive.res
@@ -1,5 +1,5 @@
 module Pervasives = {
-  include Belt.List
+  include List
   include Pervasives
 }
 
diff --git a/tests/tests/src/test_pervasives3.mjs b/tests/tests/src/test_pervasives3.mjs
index 9a926f607e1..2170f649e5a 100644
--- a/tests/tests/src/test_pervasives3.mjs
+++ b/tests/tests/src/test_pervasives3.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 let Pervasives$1 = {
   failwith: Pervasives.failwith,
@@ -22,97 +22,66 @@ let Pervasives$1 = {
   bool_of_string_opt: Pervasives.bool_of_string_opt,
   int_of_string_opt: Pervasives.int_of_string_opt,
   $at: Pervasives.$at,
-  length: Belt_List.length,
-  size: Belt_List.size,
-  head: Belt_List.head,
-  headExn: Belt_List.headExn,
-  headOrThrow: Belt_List.headOrThrow,
-  tail: Belt_List.tail,
-  tailExn: Belt_List.tailExn,
-  tailOrThrow: Belt_List.tailOrThrow,
-  add: Belt_List.add,
-  get: Belt_List.get,
-  getExn: Belt_List.getExn,
-  getOrThrow: Belt_List.getOrThrow,
-  make: Belt_List.make,
-  makeByU: Belt_List.makeByU,
-  makeBy: Belt_List.makeBy,
-  shuffle: Belt_List.shuffle,
-  drop: Belt_List.drop,
-  take: Belt_List.take,
-  splitAt: Belt_List.splitAt,
-  concat: Belt_List.concat,
-  concatMany: Belt_List.concatMany,
-  reverseConcat: Belt_List.reverseConcat,
-  flatten: Belt_List.flatten,
-  mapU: Belt_List.mapU,
-  map: Belt_List.map,
-  zip: Belt_List.zip,
-  zipByU: Belt_List.zipByU,
-  zipBy: Belt_List.zipBy,
-  mapWithIndexU: Belt_List.mapWithIndexU,
-  mapWithIndex: Belt_List.mapWithIndex,
-  fromArray: Belt_List.fromArray,
-  toArray: Belt_List.toArray,
-  reverse: Belt_List.reverse,
-  mapReverseU: Belt_List.mapReverseU,
-  mapReverse: Belt_List.mapReverse,
-  forEachU: Belt_List.forEachU,
-  forEach: Belt_List.forEach,
-  forEachWithIndexU: Belt_List.forEachWithIndexU,
-  forEachWithIndex: Belt_List.forEachWithIndex,
-  reduceU: Belt_List.reduceU,
-  reduce: Belt_List.reduce,
-  reduceWithIndexU: Belt_List.reduceWithIndexU,
-  reduceWithIndex: Belt_List.reduceWithIndex,
-  reduceReverseU: Belt_List.reduceReverseU,
-  reduceReverse: Belt_List.reduceReverse,
-  mapReverse2U: Belt_List.mapReverse2U,
-  mapReverse2: Belt_List.mapReverse2,
-  forEach2U: Belt_List.forEach2U,
-  forEach2: Belt_List.forEach2,
-  reduce2U: Belt_List.reduce2U,
-  reduce2: Belt_List.reduce2,
-  reduceReverse2U: Belt_List.reduceReverse2U,
-  reduceReverse2: Belt_List.reduceReverse2,
-  everyU: Belt_List.everyU,
-  every: Belt_List.every,
-  someU: Belt_List.someU,
-  some: Belt_List.some,
-  every2U: Belt_List.every2U,
-  every2: Belt_List.every2,
-  some2U: Belt_List.some2U,
-  some2: Belt_List.some2,
-  cmpByLength: Belt_List.cmpByLength,
-  cmpU: Belt_List.cmpU,
-  cmp: Belt_List.cmp,
-  eqU: Belt_List.eqU,
-  eq: Belt_List.eq,
-  hasU: Belt_List.hasU,
-  has: Belt_List.has,
-  getByU: Belt_List.getByU,
-  getBy: Belt_List.getBy,
-  keepU: Belt_List.keepU,
-  keep: Belt_List.keep,
-  filter: Belt_List.filter,
-  keepWithIndexU: Belt_List.keepWithIndexU,
-  keepWithIndex: Belt_List.keepWithIndex,
-  filterWithIndex: Belt_List.filterWithIndex,
-  keepMapU: Belt_List.keepMapU,
-  keepMap: Belt_List.keepMap,
-  partitionU: Belt_List.partitionU,
-  partition: Belt_List.partition,
-  unzip: Belt_List.unzip,
-  getAssocU: Belt_List.getAssocU,
-  getAssoc: Belt_List.getAssoc,
-  hasAssocU: Belt_List.hasAssocU,
-  hasAssoc: Belt_List.hasAssoc,
-  removeAssocU: Belt_List.removeAssocU,
-  removeAssoc: Belt_List.removeAssoc,
-  setAssocU: Belt_List.setAssocU,
-  setAssoc: Belt_List.setAssoc,
-  sortU: Belt_List.sortU,
-  sort: Belt_List.sort
+  length: Stdlib_List.length,
+  size: Stdlib_List.size,
+  head: Stdlib_List.head,
+  headExn: Stdlib_List.headExn,
+  headOrThrow: Stdlib_List.headOrThrow,
+  tail: Stdlib_List.tail,
+  tailExn: Stdlib_List.tailExn,
+  tailOrThrow: Stdlib_List.tailOrThrow,
+  add: Stdlib_List.add,
+  get: Stdlib_List.get,
+  getExn: Stdlib_List.getExn,
+  getOrThrow: Stdlib_List.getOrThrow,
+  make: Stdlib_List.make,
+  fromInitializer: Stdlib_List.fromInitializer,
+  shuffle: Stdlib_List.shuffle,
+  toShuffled: Stdlib_List.toShuffled,
+  drop: Stdlib_List.drop,
+  take: Stdlib_List.take,
+  splitAt: Stdlib_List.splitAt,
+  concat: Stdlib_List.concat,
+  concatMany: Stdlib_List.concatMany,
+  reverseConcat: Stdlib_List.reverseConcat,
+  flat: Stdlib_List.flat,
+  map: Stdlib_List.map,
+  zip: Stdlib_List.zip,
+  zipBy: Stdlib_List.zipBy,
+  mapWithIndex: Stdlib_List.mapWithIndex,
+  fromArray: Stdlib_List.fromArray,
+  toArray: Stdlib_List.toArray,
+  reverse: Stdlib_List.reverse,
+  mapReverse: Stdlib_List.mapReverse,
+  forEach: Stdlib_List.forEach,
+  forEachWithIndex: Stdlib_List.forEachWithIndex,
+  reduce: Stdlib_List.reduce,
+  reduceWithIndex: Stdlib_List.reduceWithIndex,
+  reduceReverse: Stdlib_List.reduceReverse,
+  mapReverse2: Stdlib_List.mapReverse2,
+  forEach2: Stdlib_List.forEach2,
+  reduce2: Stdlib_List.reduce2,
+  reduceReverse2: Stdlib_List.reduceReverse2,
+  every: Stdlib_List.every,
+  some: Stdlib_List.some,
+  every2: Stdlib_List.every2,
+  some2: Stdlib_List.some2,
+  compareLength: Stdlib_List.compareLength,
+  compare: Stdlib_List.compare,
+  equal: Stdlib_List.equal,
+  has: Stdlib_List.has,
+  includes: Stdlib_List.includes,
+  find: Stdlib_List.find,
+  filter: Stdlib_List.filter,
+  filterWithIndex: Stdlib_List.filterWithIndex,
+  filterMap: Stdlib_List.filterMap,
+  partition: Stdlib_List.partition,
+  unzip: Stdlib_List.unzip,
+  getAssoc: Stdlib_List.getAssoc,
+  hasAssoc: Stdlib_List.hasAssoc,
+  removeAssoc: Stdlib_List.removeAssoc,
+  setAssoc: Stdlib_List.setAssoc,
+  sort: Stdlib_List.sort
 };
 
 let v = Pervasives.$at;
diff --git a/tests/tests/src/test_pervasives3.res b/tests/tests/src/test_pervasives3.res
index a56aae6ad57..d9118e4a6c9 100644
--- a/tests/tests/src/test_pervasives3.res
+++ b/tests/tests/src/test_pervasives3.res
@@ -1,5 +1,5 @@
 module Pervasives = {
   include Pervasives
-  include Belt.List
+  include List
 }
 let v = Pervasives.\"@"
diff --git a/tests/tests/src/test_set.mjs b/tests/tests/src/test_set.mjs
index 61da94614f8..328c6613914 100644
--- a/tests/tests/src/test_set.mjs
+++ b/tests/tests/src/test_set.mjs
@@ -1,7 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 
 function Make(Ord) {
   let height = x => {
@@ -643,7 +643,7 @@ function Make(Ord) {
         Error: new Error()
       };
     };
-    return sub(Belt_List.length(l), l)[0];
+    return sub(Stdlib_List.length(l), l)[0];
   };
   let of_list = l => {
     if (l === 0) {
@@ -668,7 +668,7 @@ function Make(Ord) {
     let x3 = match$2.hd;
     if (match$3 !== 0) {
       if (match$3.tl !== 0) {
-        return of_sorted_list(Belt_List.sort(l, Ord.compare));
+        return of_sorted_list(Stdlib_List.sort(l, (a, b) => Ord.compare(a, b)));
       } else {
         return add(match$3.hd, add(x3, add(x2, add(x1, singleton(x0)))));
       }
diff --git a/tests/tests/src/test_set.res b/tests/tests/src/test_set.res
index a4831097083..852f1f40e9c 100644
--- a/tests/tests/src/test_set.res
+++ b/tests/tests/src/test_set.res
@@ -501,7 +501,7 @@ module Make = (Ord: OrderedType) => {
         }
       }
 
-    fst(sub(Belt.List.length(l), l))
+    fst(sub(List.length(l), l))
   }
 
   let of_list = l =>
@@ -512,7 +512,7 @@ module Make = (Ord: OrderedType) => {
     | list{x0, x1, x2} => add(x2, add(x1, singleton(x0)))
     | list{x0, x1, x2, x3} => add(x3, add(x2, add(x1, singleton(x0))))
     | list{x0, x1, x2, x3, x4} => add(x4, add(x3, add(x2, add(x1, singleton(x0)))))
-    | _ => of_sorted_list(l->Belt.List.sort(Ord.compare))
+    | _ => of_sorted_list(l->List.sort((a, b) => Ord.compare(a, b)->Int.toFloat))
     }
 }
 module N = {
diff --git a/tests/tests/src/test_simple_include.mjs b/tests/tests/src/test_simple_include.mjs
index b0756cde6aa..426c7d4306d 100644
--- a/tests/tests/src/test_simple_include.mjs
+++ b/tests/tests/src/test_simple_include.mjs
@@ -1,6 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 let v = {
   contents: 32
@@ -22,231 +22,84 @@ let NN = {
   v: v$1
 };
 
-let get = Belt_Array.get;
+let make = Stdlib_Array.make;
 
-let getExn = Belt_Array.getExn;
+let fromInitializer = Stdlib_Array.fromInitializer;
 
-let getOrThrow = Belt_Array.getOrThrow;
+let equal = Stdlib_Array.equal;
 
-let set = Belt_Array.set;
+let compare = Stdlib_Array.compare;
 
-let setExn = Belt_Array.setExn;
+let isEmpty = Stdlib_Array.isEmpty;
 
-let setOrThrow = Belt_Array.setOrThrow;
+let concatAll = Stdlib_Array.concatAll;
 
-let shuffleInPlace = Belt_Array.shuffleInPlace;
+let indexOfOpt = Stdlib_Array.indexOfOpt;
 
-let shuffle = Belt_Array.shuffle;
+let lastIndexOfOpt = Stdlib_Array.lastIndexOfOpt;
 
-let reverseInPlace = Belt_Array.reverseInPlace;
+let reduce = Stdlib_Array.reduce;
 
-let reverse = Belt_Array.reverse;
+let reduceWithIndex = Stdlib_Array.reduceWithIndex;
 
-let make = Belt_Array.make;
+let reduceRight = Stdlib_Array.reduceRight;
 
-let range = Belt_Array.range;
+let reduceRightWithIndex = Stdlib_Array.reduceRightWithIndex;
 
-let rangeBy = Belt_Array.rangeBy;
+let findIndexOpt = Stdlib_Array.findIndexOpt;
 
-let makeByU = Belt_Array.makeByU;
+let findLastIndexOpt = Stdlib_Array.findLastIndexOpt;
 
-let makeBy = Belt_Array.makeBy;
+let filterMap = Stdlib_Array.filterMap;
 
-let makeByAndShuffleU = Belt_Array.makeByAndShuffleU;
+let filterMapWithIndex = Stdlib_Array.filterMapWithIndex;
 
-let makeByAndShuffle = Belt_Array.makeByAndShuffle;
+let keepSome = Stdlib_Array.keepSome;
 
-let zip = Belt_Array.zip;
+let toShuffled = Stdlib_Array.toShuffled;
 
-let zipByU = Belt_Array.zipByU;
+let shuffle = Stdlib_Array.shuffle;
 
-let zipBy = Belt_Array.zipBy;
+let findMap = Stdlib_Array.findMap;
 
-let unzip = Belt_Array.unzip;
+let zip = Stdlib_Array.zip;
 
-let concat = Belt_Array.concat;
+let zipBy = Stdlib_Array.zipBy;
 
-let concatMany = Belt_Array.concatMany;
+let partition = Stdlib_Array.partition;
 
-let slice = Belt_Array.slice;
+let unzip = Stdlib_Array.unzip;
 
-let sliceToEnd = Belt_Array.sliceToEnd;
-
-let fill = Belt_Array.fill;
-
-let blit = Belt_Array.blit;
-
-let blitUnsafe = Belt_Array.blitUnsafe;
-
-let forEachU = Belt_Array.forEachU;
-
-let forEach = Belt_Array.forEach;
-
-let mapU = Belt_Array.mapU;
-
-let map = Belt_Array.map;
-
-let flatMapU = Belt_Array.flatMapU;
-
-let flatMap = Belt_Array.flatMap;
-
-let getByU = Belt_Array.getByU;
-
-let getBy = Belt_Array.getBy;
-
-let getIndexByU = Belt_Array.getIndexByU;
-
-let getIndexBy = Belt_Array.getIndexBy;
-
-let keepU = Belt_Array.keepU;
-
-let keep = Belt_Array.keep;
-
-let keepWithIndexU = Belt_Array.keepWithIndexU;
-
-let keepWithIndex = Belt_Array.keepWithIndex;
-
-let keepMapU = Belt_Array.keepMapU;
-
-let keepMap = Belt_Array.keepMap;
-
-let forEachWithIndexU = Belt_Array.forEachWithIndexU;
-
-let forEachWithIndex = Belt_Array.forEachWithIndex;
-
-let mapWithIndexU = Belt_Array.mapWithIndexU;
-
-let mapWithIndex = Belt_Array.mapWithIndex;
-
-let partitionU = Belt_Array.partitionU;
-
-let partition = Belt_Array.partition;
-
-let reduceU = Belt_Array.reduceU;
-
-let reduce = Belt_Array.reduce;
-
-let reduceReverseU = Belt_Array.reduceReverseU;
-
-let reduceReverse = Belt_Array.reduceReverse;
-
-let reduceReverse2U = Belt_Array.reduceReverse2U;
-
-let reduceReverse2 = Belt_Array.reduceReverse2;
-
-let reduceWithIndexU = Belt_Array.reduceWithIndexU;
-
-let reduceWithIndex = Belt_Array.reduceWithIndex;
-
-let joinWithU = Belt_Array.joinWithU;
-
-let joinWith = Belt_Array.joinWith;
-
-let someU = Belt_Array.someU;
-
-let some = Belt_Array.some;
-
-let everyU = Belt_Array.everyU;
-
-let every = Belt_Array.every;
-
-let every2U = Belt_Array.every2U;
-
-let every2 = Belt_Array.every2;
-
-let some2U = Belt_Array.some2U;
-
-let some2 = Belt_Array.some2;
-
-let cmpU = Belt_Array.cmpU;
-
-let cmp = Belt_Array.cmp;
-
-let eqU = Belt_Array.eqU;
-
-let eq = Belt_Array.eq;
-
-let initU = Belt_Array.initU;
-
-let init = Belt_Array.init;
+let last = Stdlib_Array.last;
 
 let a = 3;
 
 export {
-  get,
-  getExn,
-  getOrThrow,
-  set,
-  setExn,
-  setOrThrow,
-  shuffleInPlace,
-  shuffle,
-  reverseInPlace,
-  reverse,
   make,
-  range,
-  rangeBy,
-  makeByU,
-  makeBy,
-  makeByAndShuffleU,
-  makeByAndShuffle,
+  fromInitializer,
+  equal,
+  compare,
+  isEmpty,
+  concatAll,
+  indexOfOpt,
+  lastIndexOfOpt,
+  reduce,
+  reduceWithIndex,
+  reduceRight,
+  reduceRightWithIndex,
+  findIndexOpt,
+  findLastIndexOpt,
+  filterMap,
+  filterMapWithIndex,
+  keepSome,
+  toShuffled,
+  shuffle,
+  findMap,
   zip,
-  zipByU,
   zipBy,
-  unzip,
-  concat,
-  concatMany,
-  slice,
-  sliceToEnd,
-  fill,
-  blit,
-  blitUnsafe,
-  forEachU,
-  forEach,
-  mapU,
-  map,
-  flatMapU,
-  flatMap,
-  getByU,
-  getBy,
-  getIndexByU,
-  getIndexBy,
-  keepU,
-  keep,
-  keepWithIndexU,
-  keepWithIndex,
-  keepMapU,
-  keepMap,
-  forEachWithIndexU,
-  forEachWithIndex,
-  mapWithIndexU,
-  mapWithIndex,
-  partitionU,
   partition,
-  reduceU,
-  reduce,
-  reduceReverseU,
-  reduceReverse,
-  reduceReverse2U,
-  reduceReverse2,
-  reduceWithIndexU,
-  reduceWithIndex,
-  joinWithU,
-  joinWith,
-  someU,
-  some,
-  everyU,
-  every,
-  every2U,
-  every2,
-  some2U,
-  some2,
-  cmpU,
-  cmp,
-  eqU,
-  eq,
-  initU,
-  init,
+  unzip,
+  last,
   N,
   NN,
   a,
diff --git a/tests/tests/src/test_simple_include.res b/tests/tests/src/test_simple_include.res
index 6586d3401dd..d6325f00631 100644
--- a/tests/tests/src/test_simple_include.res
+++ b/tests/tests/src/test_simple_include.res
@@ -1,4 +1,4 @@
-include Belt.Array
+include Array
 
 include {
   assert(1 + 2 == 3)
diff --git a/tests/tests/src/test_while_closure.mjs b/tests/tests/src/test_while_closure.mjs
index dd30b138fd2..7f248c947eb 100644
--- a/tests/tests/src/test_while_closure.mjs
+++ b/tests/tests/src/test_while_closure.mjs
@@ -1,12 +1,12 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
+import * as Stdlib_Array from "@rescript/runtime/lib/es6/Stdlib_Array.mjs";
 
 let v = {
   contents: 0
 };
 
-let arr = Belt_Array.make(10, () => {});
+let arr = Stdlib_Array.make(10, () => {});
 
 function f() {
   let n = 0;
@@ -21,7 +21,7 @@ function f() {
 
 f();
 
-Belt_Array.forEach(arr, x => x());
+arr.forEach(x => x());
 
 console.log(v.contents.toString());
 
diff --git a/tests/tests/src/test_while_closure.res b/tests/tests/src/test_while_closure.res
index 61cd24cadd4..0d31a9f0aec 100644
--- a/tests/tests/src/test_while_closure.res
+++ b/tests/tests/src/test_while_closure.res
@@ -38,7 +38,7 @@ This means inline is tricky in javascript, here we try to inline [_loop]?
 
 let v = ref(0)
 let count = 10
-let arr = Belt.Array.make(count, _ => ())
+let arr = Array.make(~length=count, _ => ())
 let f = () => {
   let n = ref(0)
   while n.contents < count {
@@ -50,7 +50,7 @@ let f = () => {
 
 let () = {
   f()
-  arr->Belt.Array.forEach(x => x())
+  arr->Array.forEach(x => x())
   v.contents->Int.toString->Console.log
   assert(v.contents == 45)
 }
diff --git a/tests/tests/src/topsort_test.mjs b/tests/tests/src/topsort_test.mjs
index e368359f48f..d75ea6233a8 100644
--- a/tests/tests/src/topsort_test.mjs
+++ b/tests/tests/src/topsort_test.mjs
@@ -1,8 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
 import * as Pervasives from "@rescript/runtime/lib/es6/Pervasives.mjs";
-import * as Belt_SetString from "@rescript/runtime/lib/es6/Belt_SetString.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
 import * as Primitive_exceptions from "@rescript/runtime/lib/es6/Primitive_exceptions.mjs";
 
@@ -57,7 +56,7 @@ let graph = {
 };
 
 function nexts(x, g) {
-  return Belt_List.reduce(g, /* [] */0, (acc, param) => {
+  return Stdlib_List.reduce(g, /* [] */0, (acc, param) => {
     if (param[0] === x) {
       return {
         hd: param[1],
@@ -74,11 +73,11 @@ function dfs1(_nodes, graph, _visited) {
     let visited = _visited;
     let nodes = _nodes;
     if (nodes === 0) {
-      return Belt_List.reverse(visited);
+      return Stdlib_List.reverse(visited);
     }
     let xs = nodes.tl;
     let x = nodes.hd;
-    if (Belt_List.has(visited, x, (prim0, prim1) => prim0 === prim1)) {
+    if (Stdlib_List.has(visited, x, (prim0, prim1) => prim0 === prim1)) {
       _nodes = xs;
       continue;
     }
@@ -121,7 +120,7 @@ if (!Primitive_object.equal(dfs1({
     RE_EXN_ID: "Assert_failure",
     _1: [
       "topsort_test.res",
-      38,
+      36,
       2
     ],
     Error: new Error()
@@ -159,7 +158,7 @@ if (!Primitive_object.equal(dfs1({
     RE_EXN_ID: "Assert_failure",
     _1: [
       "topsort_test.res",
-      41,
+      39,
       2
     ],
     Error: new Error()
@@ -176,7 +175,7 @@ function dfs2(nodes, graph, visited) {
       }
       let xs = nodes.tl;
       let x = nodes.hd;
-      if (Belt_List.has(visited, x, (prim0, prim1) => prim0 === prim1)) {
+      if (Stdlib_List.has(visited, x, (prim0, prim1) => prim0 === prim1)) {
         _nodes = xs;
         continue;
       }
@@ -188,7 +187,7 @@ function dfs2(nodes, graph, visited) {
       continue;
     };
   };
-  return Belt_List.reverse(aux(nodes, graph, visited));
+  return Stdlib_List.reverse(aux(nodes, graph, visited));
 }
 
 if (!Primitive_object.equal(dfs2({
@@ -220,7 +219,7 @@ if (!Primitive_object.equal(dfs2({
     RE_EXN_ID: "Assert_failure",
     _1: [
       "topsort_test.res",
-      60,
+      58,
       2
     ],
     Error: new Error()
@@ -256,7 +255,7 @@ if (!Primitive_object.equal(dfs2({
     RE_EXN_ID: "Assert_failure",
     _1: [
       "topsort_test.res",
-      61,
+      59,
       2
     ],
     Error: new Error()
@@ -268,16 +267,16 @@ function dfs3(nodes, graph) {
     contents: /* [] */0
   };
   let aux = (node, graph) => {
-    if (!Belt_List.has(visited.contents, node, (prim0, prim1) => prim0 === prim1)) {
+    if (!Stdlib_List.has(visited.contents, node, (prim0, prim1) => prim0 === prim1)) {
       visited.contents = {
         hd: node,
         tl: visited.contents
       };
-      return Belt_List.forEach(nexts(node, graph), x => aux(x, graph));
+      return Stdlib_List.forEach(nexts(node, graph), x => aux(x, graph));
     }
   };
-  Belt_List.forEach(nodes, node => aux(node, graph));
-  return Belt_List.reverse(visited.contents);
+  Stdlib_List.forEach(nodes, node => aux(node, graph));
+  return Stdlib_List.reverse(visited.contents);
 }
 
 if (!Primitive_object.equal(dfs3({
@@ -309,7 +308,7 @@ if (!Primitive_object.equal(dfs3({
     RE_EXN_ID: "Assert_failure",
     _1: [
       "topsort_test.res",
-      77,
+      75,
       2
     ],
     Error: new Error()
@@ -345,7 +344,7 @@ if (!Primitive_object.equal(dfs3({
     RE_EXN_ID: "Assert_failure",
     _1: [
       "topsort_test.res",
-      78,
+      76,
       2
     ],
     Error: new Error()
@@ -395,17 +394,17 @@ function unsafe_topsort(graph) {
     contents: /* [] */0
   };
   let sort_node = node => {
-    if (Belt_List.has(visited.contents, node, (prim0, prim1) => prim0 === prim1)) {
+    if (Stdlib_List.has(visited.contents, node, (prim0, prim1) => prim0 === prim1)) {
       return;
     }
     let nodes = nexts(node, graph);
-    Belt_List.forEach(nodes, sort_node);
+    Stdlib_List.forEach(nodes, sort_node);
     visited.contents = {
       hd: node,
       tl: visited.contents
     };
   };
-  Belt_List.forEach(graph, param => sort_node(param[0]));
+  Stdlib_List.forEach(graph, param => sort_node(param[0]));
   return visited.contents;
 }
 
@@ -432,7 +431,7 @@ if (!Primitive_object.equal(unsafe_topsort(grwork), {
     RE_EXN_ID: "Assert_failure",
     _1: [
       "topsort_test.res",
-      115,
+      113,
       9
     ],
     Error: new Error()
@@ -445,34 +444,25 @@ function pathsort(graph) {
   let visited = {
     contents: /* [] */0
   };
-  let empty_path = [
-    undefined,
-    /* [] */0
-  ];
-  let $plus$great = (node, param) => {
-    let stack = param[1];
-    let set = param[0];
-    if (Belt_SetString.has(set, node)) {
+  let $plus$great = (node, path) => {
+    if (Stdlib_List.has(path, node, (prim0, prim1) => prim0 === prim1)) {
       throw {
         RE_EXN_ID: Cycle,
         _1: {
           hd: node,
-          tl: stack
+          tl: path
         },
         Error: new Error()
       };
     }
-    return [
-      Belt_SetString.add(set, node),
-      {
-        hd: node,
-        tl: stack
-      }
-    ];
+    return {
+      hd: node,
+      tl: path
+    };
   };
-  let sort_nodes = (path, nodes) => Belt_List.forEach(nodes, node => sort_node(path, node));
+  let sort_nodes = (path, nodes) => Stdlib_List.forEach(nodes, node => sort_node(path, node));
   let sort_node = (path, node) => {
-    if (!Belt_List.has(visited.contents, node, (prim0, prim1) => prim0 === prim1)) {
+    if (!Stdlib_List.has(visited.contents, node, (prim0, prim1) => prim0 === prim1)) {
       sort_nodes($plus$great(node, path), nexts(node, graph));
       visited.contents = {
         hd: node,
@@ -481,7 +471,7 @@ function pathsort(graph) {
       return;
     }
   };
-  Belt_List.forEach(graph, param => sort_node(empty_path, param[0]));
+  Stdlib_List.forEach(graph, param => sort_node(/* [] */0, param[0]));
   return visited.contents;
 }
 
@@ -508,7 +498,7 @@ if (!Primitive_object.equal(pathsort(grwork), {
     RE_EXN_ID: "Assert_failure",
     _1: [
       "topsort_test.res",
-      147,
+      141,
       9
     ],
     Error: new Error()
@@ -527,7 +517,7 @@ try {
     RE_EXN_ID: "Assert_failure",
     _1: [
       "topsort_test.res",
-      151,
+      145,
       2
     ],
     Error: new Error()
@@ -563,7 +553,7 @@ try {
       RE_EXN_ID: "Assert_failure",
       _1: [
         "topsort_test.res",
-        154,
+        148,
         7
       ],
       Error: new Error()
@@ -571,8 +561,6 @@ try {
   }
 }
 
-let String_set;
-
 export {
   graph,
   nexts,
@@ -581,7 +569,6 @@ export {
   dfs3,
   grwork,
   unsafe_topsort,
-  String_set,
   Cycle,
   pathsort,
 }
diff --git a/tests/tests/src/topsort_test.res b/tests/tests/src/topsort_test.res
index 06866b785a9..a7bd936d148 100644
--- a/tests/tests/src/topsort_test.res
+++ b/tests/tests/src/topsort_test.res
@@ -1,5 +1,3 @@
-open Belt
-
 type graph = list<(string, string)>
 
 let graph: graph = list{
@@ -114,21 +112,17 @@ let unsafe_topsort = graph => {
 
 let () = assert(unsafe_topsort(grwork) == list{"wake", "shower", "dress", "eat", "washup", "go"})
 
-module String_set = Belt.Set.String
 exception Cycle(list<string>)
 let pathsort = graph => {
   let visited = ref(list{})
-  let empty_path = (String_set.empty, list{})
-  let \"+>" = (node, (set, stack)) =>
-    if String_set.has(set, node) {
-      throw(Cycle(list{node, ...stack}))
+  let empty_path = list{}
+  let \"+>" = (node, path) =>
+    if List.has(path, node, \"==") {
+      throw(Cycle(list{node, ...path}))
     } else {
-      (String_set.add(set, node), list{node, ...stack})
+      list{node, ...path}
     }
 
-  /* let check node (set,stack) = 
-      if String_set.mem node set then 
-        raise (Cycle (node::stack))  in */
   let rec sort_nodes = (path, nodes) => nodes->List.forEach(node => sort_node(path, node))
   and sort_node = (path, node) =>
     if !List.has(visited.contents, node, \"==") {
diff --git a/tests/tests/src/uncurried_cast.mjs b/tests/tests/src/uncurried_cast.mjs
index 28135f925b3..6b69ccb0ef7 100644
--- a/tests/tests/src/uncurried_cast.mjs
+++ b/tests/tests/src/uncurried_cast.mjs
@@ -1,13 +1,13 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as Primitive_exceptions from "@rescript/runtime/lib/es6/Primitive_exceptions.mjs";
 
 function raise(e) {
   throw e;
 }
 
-let map = Belt_List.map;
+let map = Stdlib_List.map;
 
 let List = {
   map: map
@@ -27,7 +27,7 @@ function testRaise() {
   };
 }
 
-let l = Belt_List.map({
+let l = Stdlib_List.map({
   hd: 1,
   tl: {
     hd: 2,
@@ -36,7 +36,7 @@ let l = Belt_List.map({
 }, x => x + 1 | 0);
 
 function partial(x) {
-  return Belt_List.map({
+  return Stdlib_List.map({
     hd: 1,
     tl: {
       hd: 2,
@@ -68,7 +68,7 @@ function testRaise$1() {
   };
 }
 
-let l$1 = Belt_List.map({
+let l$1 = Stdlib_List.map({
   hd: 1,
   tl: {
     hd: 2,
@@ -77,7 +77,7 @@ let l$1 = Belt_List.map({
 }, x => x + 1 | 0);
 
 function partial$1(extra) {
-  return Belt_List.map({
+  return Stdlib_List.map({
     hd: 1,
     tl: {
       hd: 2,
diff --git a/tests/tests/src/uncurried_cast.res b/tests/tests/src/uncurried_cast.res
index f7244ec081f..a44083c404e 100644
--- a/tests/tests/src/uncurried_cast.res
+++ b/tests/tests/src/uncurried_cast.res
@@ -2,7 +2,7 @@ module Uncurried = {
   let raise = e => throw(e)
 
   module List = {
-    let map = (l, f) => Belt.List.map(l, f)
+    let map = (l, f) => List.map(l, f)
   }
 }
 
diff --git a/tests/tests/src/webpack_config.mjs b/tests/tests/src/webpack_config.mjs
index 8988a659b9b..3249828cfda 100644
--- a/tests/tests/src/webpack_config.mjs
+++ b/tests/tests/src/webpack_config.mjs
@@ -4,7 +4,7 @@ import * as List from "List";
 import * as List$1 from "reactV";
 import * as List$2 from "reactX";
 import * as Local from "./local";
-import * as Belt_List from "@rescript/runtime/lib/es6/Belt_List.mjs";
+import * as Stdlib_List from "@rescript/runtime/lib/es6/Stdlib_List.mjs";
 import * as WebpackConfigJs from "../../../webpack.config.js";
 import * as WebpackMiddlewareConfigJs from "../../../webpack.middleware.config.js";
 
@@ -55,7 +55,7 @@ function f() {
 
 List.xx();
 
-Belt_List.length({
+Stdlib_List.length({
   hd: 1,
   tl: {
     hd: 2,
@@ -63,7 +63,7 @@ Belt_List.length({
   }
 });
 
-Belt_List.length(/* [] */0);
+Stdlib_List.length(/* [] */0);
 
 function ff(prim) {
   return Local.ff();
diff --git a/tests/tests/src/webpack_config.res b/tests/tests/src/webpack_config.res
index 6928a298c87..81d3a589f62 100644
--- a/tests/tests/src/webpack_config.res
+++ b/tests/tests/src/webpack_config.res
@@ -1,5 +1,3 @@
-open Belt
-
 module type Config = {
   let configx: JSON.t
 }
diff --git a/yarn.lock b/yarn.lock
index a687c28be73..e8f0072c125 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -434,6 +434,18 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@rescript/belt@workspace:^, @rescript/belt@workspace:packages/@rescript/belt":
+  version: 0.0.0-use.local
+  resolution: "@rescript/belt@workspace:packages/@rescript/belt"
+  dependencies:
+    "@rescript/runtime": "workspace:^"
+    rescript: "workspace:^"
+  peerDependencies:
+    "@rescript/runtime": "workspace:^"
+    rescript: "workspace:^"
+  languageName: unknown
+  linkType: soft
+
 "@rescript/darwin-arm64@npm:12.3.0":
   version: 12.3.0
   resolution: "@rescript/darwin-arm64@npm:12.3.0"
@@ -501,7 +513,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@rescript/runtime@workspace:packages/@rescript/runtime":
+"@rescript/runtime@workspace:^, @rescript/runtime@workspace:packages/@rescript/runtime":
   version: 0.0.0-use.local
   resolution: "@rescript/runtime@workspace:packages/@rescript/runtime"
   dependencies:
@@ -851,15 +863,27 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@tests/analysis@workspace:tests/analysis_tests/tests"
   dependencies:
+    "@rescript/belt": "workspace:^"
     "@rescript/react": "workspace:^"
     rescript: "workspace:^"
   languageName: unknown
   linkType: soft
 
+"@tests/belt@workspace:tests/belt_tests":
+  version: 0.0.0-use.local
+  resolution: "@tests/belt@workspace:tests/belt_tests"
+  dependencies:
+    "@rescript/belt": "workspace:^"
+    mocha: "npm:11.7.6"
+    rescript: "workspace:^"
+  languageName: unknown
+  linkType: soft
+
 "@tests/docstring-tests@workspace:^, @tests/docstring-tests@workspace:tests/docstring_tests":
   version: 0.0.0-use.local
   resolution: "@tests/docstring-tests@workspace:tests/docstring_tests"
   dependencies:
+    "@rescript/belt": "workspace:^"
     "@rescript/react": "workspace:^"
     rescript: "workspace:^"
   languageName: unknown
@@ -877,6 +901,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@tests/gentype-react-example@workspace:tests/gentype_tests/typescript-react-example"
   dependencies:
+    "@rescript/belt": "workspace:^"
     "@rescript/react": "workspace:^"
     "@types/react": "npm:^19.2.18"
     "@types/react-dom": "npm:^19.2.4"
@@ -925,6 +950,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@tests/reanalyze-deadcode@workspace:tests/analysis_tests/tests-reanalyze/deadcode"
   dependencies:
+    "@rescript/belt": "workspace:^"
     "@rescript/react": "workspace:^"
     rescript: "workspace:^"
   languageName: unknown
@@ -2615,6 +2641,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "playground@workspace:packages/playground"
   dependencies:
+    "@rescript/belt": "workspace:^"
     "@rescript/react": "workspace:^"
     "@rollup/plugin-node-resolve": "npm:^16.0.0"
     h3: "npm:2.0.1-rc.26"
@@ -2720,6 +2747,9 @@ __metadata:
 "rescript-commonjs-tests@workspace:tests/commonjs_tests":
   version: 0.0.0-use.local
   resolution: "rescript-commonjs-tests@workspace:tests/commonjs_tests"
+  dependencies:
+    "@rescript/belt": "workspace:^"
+    rescript: "workspace:^"
   languageName: unknown
   linkType: soft