General purpose web IDE for MLscript by chengluyu · Pull Request #367 · hkust-taco/mlscript

chengluyu · 2025-12-16T11:12:12Z

Note

The web IDE is (manually) deployed and accessible at https://mlscript.fun.

Planned Tasks

Support importing standard libraries through import "std/Stack.mls" instead of using relative paths.
Rewrite as many web components as possible with MLscript.
Generate deployable compiled project source files.

Bugs to be fixed

The file explorer doesn't navigate when using Firefox and Safari.

CAG2Mark · 2025-12-17T07:19:22Z

FYI: pressing tab does not insert whitespace, but instead navigates to the next element

LPTK · 2025-12-18T05:26:20Z

+  val pwd = os.pwd
+  val workingDir = pwd
+
+  val mainTestDir = workingDir/"hkmc2"/"shared"/"src"/"test"
+  val stdPath = mainTestDir / "mlscript-compile"
+
+  val compilerPaths = new MLsCompiler.Paths:
+    val preludeFile = mainTestDir / "mlscript" / "decls" / "Prelude.mls"
+    val runtimeFile = mainTestDir / "mlscript-compile" / "Runtime.mjs"
+    val termFile = mainTestDir / "mlscript-compile" / "Term.mjs"
+
+  val nodeModulesPath = workingDir / "node_modules"


Any reason to move all of these in the companion? Doing so means they can no longer be overridden by other users of the test suite. (There is just one example with BenchTestState for now.)

LPTK · 2025-12-18T05:27:03Z

 import hkmc2.semantics.*
 import hkmc2.syntax.Keyword.`override`
 import semantics.Elaborator.{Ctx, State}
+import hkmc2.io.Path


LPTK · 2025-12-18T05:28:21Z

-
+      raise:
+        ErrorReport(msg"Cannot resolve the import path ${actualFile.toString}" -> rawPath.toLoc :: Nil)
+      Import(sym, rawPath.value, actualFile)


Suggested change

Import(sym, rawPath.value, actualFile)

Import(sym, rawPath.value, actualFile)

LPTK · 2025-12-18T05:28:43Z

Beautiful! :^)

LPTK · 2025-12-18T05:30:34Z

      catch ex =>
        // System.err.println("Unexpected error in watcher: " + ex)
-        // ex.printStackTrace()
+        ex.printStackTrace()


Isn't the stack trace already shown when throw ex propagates to the top-level?

FlandiaYingman · 2025-12-27T15:52:00Z

How about having a special syntax to denote that std is a predefined shortcut instead of an actual place? Say something similar to TypeScript's @ prefix for predefined paths and Typst's @preview or @local. We can have @std.

LPTK · 2025-12-27T16:09:57Z

I didn't know TypeScript did that. It's not strictly necessary (since paths not starting with . are treated as absolute and the others are for libs/predefined folders), but it could be a nice way of getting some more disambiguation. WDYT @chengluyu?

chengluyu · 2025-12-28T07:00:44Z

How about having a special syntax to denote that std is a predefined shortcut instead of an actual place? Say something similar to TypeScript's @ prefix for predefined paths and Typst's @preview or @local. We can have @std.

@ usually represents the scope name. You can register an organization in a package registry like npm, and the packages published within that organization must include this prefix when importing, for example @mlscript/ucs-demo-build (the MLscript compiler package I published for the UCS web demo).

The practice you mentioned should be more or less like, in TypeScript projects, some people use paths to shorten long path names. For example, the usage here: https://github.com/Netflix/metaflow-ui/blob/ed4c2d34f12e7c4ac0020978bcfb8c8c2d938c6b/tsconfig.json#L28-L37

I plan to implement path remapping options like this. So that projects in mlscript-apps can resolve to the std in other directories.

I didn't know TypeScript did that. It's not strictly necessary (since paths not starting with . are treated as absolute and the others are for libs/predefined folders), but it could be a nice way of getting some more disambiguation. WDYT @chengluyu?

As to whether we should use @std, I think this is not bad.

Resolve merge fallout around module import aliases, split test runners, and test-folder ownership.

LPTK · 2026-05-18T01:02:23Z

+```mlscript
+  fun fromMaybe(x) = if x is
+    Some(value) then value
+    ~Some(_) then default


This can be just ~Some then ...

LPTK · 2026-05-18T01:05:14Z

-  }
+  mut
+    'type: "compile-success"
+    // BUG: `:field` puns currently miscompile in multiline `mut` records here.


Should open an issue.

LPTK · 2026-05-18T01:33:31Z

+    if this.unsubscribe is
+      Absent then ()
+      unsubscribe then unsubscribe()


Should use ~Absent and do instead. I was better before!

LPTK · 2026-05-18T01:33:52Z

-      else this.openTabs.get(this.activeTabId)
+  fun handleFsEventForTab(tabId, tab, event) = if
+    tab.path !== event.path then ()
+    event.("type") is


event.'type

LPTK · 2026-05-18T01:34:24Z

+  fun handleFsEventForTab(tabId, tab, event) = if
+    tab.path !== event.path then ()
+    event.("type") is
+      "delete" then this.closeTab(tabId)


LPTK · 2026-05-18T01:36:21Z

+    not Number.isFinite(timestamp) then ""
+    else
+      let divisions = [
+        (amount: 60, unit: "seconds"),


All end-of-line commas that do not introduce a nested block are unnecessary.

LPTK · 2026-05-18T01:37:01Z

-      endLine: endPos.line,
-      endColumn: endPos.column,
+    mut
+      startLine: (startPos.line)


Are the parens really necessary?

LPTK · 2026-05-18T01:37:36Z

-    else node.children
+fun childrenOf(node) = if node.children is
+  Absent then []
+  ~Absent as children then children


LPTK · 2026-05-19T02:04:23Z

+
+#### Prefer quoted field selection for keyword-like fields
+
+When selecting a field whose name is keyword-like, prefer quoted field selection


Lol it's not about being keyword-like, it's about being a single word/identifier.

LPTK · 2026-05-19T02:05:25Z

-        set this.activeTabId = tabId
-        tab.editorView.focus()
+    if selectedTab is ~Absent as tab do
+      tab.editorDiv.classList.add("active")


LPTK · 2026-05-19T02:05:56Z

+      this.openTabs.delete(tabId)
+      if this.activeTabId === tabId do
+        let remainingTabs = Array.from(this.openTabs.keys())
+        if


Strange newline.

chengluyu added 2 commits December 16, 2025 16:45

Prototype the Web IDE

e1146fa

Move web IDE to apps and create a runner for apps

ecb5737

chengluyu changed the base branch from mlscript to hkmc2 December 16, 2025 11:12

chengluyu added 3 commits December 18, 2025 10:18

Add path resolution logic

ec96a8d

Support module resolution

94fe366

Commit the unstable uid changes to make CI happy

fc93faa

LPTK reviewed Dec 18, 2025

View reviewed changes

Specify files that need to be vendored

3973fa1

LPTK force-pushed the hkmc2 branch 2 times, most recently from 46c5ce1 to 414cf0c Compare March 10, 2026 15:42

LPTK force-pushed the hkmc2 branch 2 times, most recently from f5b9c17 to 323afbd Compare April 13, 2026 10:20

chengluyu added 6 commits May 9, 2026 20:26

Integrate hkmc2 updates into web-ide

2806ff0

Resolve merge fallout around module import aliases, split test runners, and test-folder ownership.

Split package tests from app tests

1971fe5

Implement package vendoring prototype

63251d7

Validate package graph vendoring

dbbd53e

Display relative paths when building packages

2234cbb

Get rid of unnecessary imports

f7e07c0

LPTK reviewed May 10, 2026

View reviewed changes

Comment thread hkmc2/shared/src/test/mlscript/codegen/QQImport.mls Outdated

chengluyu added 3 commits May 10, 2026 17:32

Make parser preprocessing stack-safe for Scala.js

07cb037

Harden Web IDE browser compiler path

6095a1c

Rewrite Web IDE filesystem in MLscript

c9e507f

LPTK reviewed May 17, 2026

View reviewed changes

Comment thread hkmc2/shared/src/test/mlscript-packages/web-ide/components/EditorPanel.mls Outdated

LPTK reviewed May 17, 2026

View reviewed changes

Comment thread hkmc2/shared/src/test/mlscript-packages/web-ide/components/ToolbarPanel.mls Outdated

chengluyu added 10 commits May 17, 2026 23:17

Add sidebar activity rails

d6eb821

Use not idioms in Web IDE MLscript

a515dd4

Use action do idioms in Web IDE MLscript

4ee8b8f

Use quoted identifier object idioms in Web IDE MLscript

3c71190

Use indentation object idioms in Web IDE MLscript

f53f7f3

Use of-call idioms selectively in Web IDE MLscript

9bf5a96

Inline editor theme rule specs

323060f

Apply idiomatic MLscript Web IDE rewrites

867affb

Deploy Web IDE to Cloudflare Workers

71ac7ca

Add Web IDE branch preview deployments

fb6061a

LPTK reviewed May 18, 2026

View reviewed changes

chengluyu added 7 commits May 18, 2026 14:20

Document additional idiomatic MLscript rules

af6c7fe

Complete negated constructor wildcard pass

a5a9c8f

Use present-case do for optional effects

af3792a

Use quoted field selection in Web IDE

3ebfbb1

Drop unnecessary end-of-line commas

5d8b0a9

Drop unnecessary selection parentheses

5d6a944

Use variable fallbacks for complement patterns

378758b

LPTK reviewed May 19, 2026

View reviewed changes

	Import(sym, rawPath.value, actualFile)
	Import(sym, rawPath.value, actualFile)


		#### Prefer quoted field selection for keyword-like fields

		When selecting a field whose name is keyword-like, prefer quoted field selection

Conversation

chengluyu commented Dec 16, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Planned Tasks

Bugs to be fixed

Uh oh!

CAG2Mark commented Dec 17, 2025

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

FlandiaYingman commented Dec 27, 2025

Uh oh!

LPTK commented Dec 27, 2025

Uh oh!

chengluyu commented Dec 28, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

🙀

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

chengluyu commented Dec 16, 2025 •

edited

Loading

chengluyu commented Dec 28, 2025 •

edited

Loading