rrbvec

rrbvec is a persistent RRB vector implementation for OCaml. It supports native OCaml, js_of_ocaml, and Melange, and provides efficient indexed access, updates, appends, and concatenation while preserving previous versions.

Example

let vector = Rrbvec.of_list [ 1; 2; 3 ]
let updated = Rrbvec.set vector 1 10

let () =
  assert (Rrbvec.to_list vector = [ 1; 2; 3 ]);
  assert (Rrbvec.to_list updated = [ 1; 10; 3 ])

Time complexity

Let n be the vector length and m the length of a second vector or input collection. RRB trees use a branching factor of 32, so logarithmic operations have a very shallow log32 path.

API	Time complexity	Notes
length, is_empty	O(1)	Stored in the vector header.
nth, nth_opt	O(log32 n) worst case	O(1) when the value is in an edge buffer.
set	O(log32 n) worst case	Copies only the path to the changed value.
push_front, push_back	O(log32 n) worst case	O(1) while the corresponding edge buffer has room.
pop_front, pop_back	O(log32 n) worst case	O(1) when no tree refill is required.
peek_front, peek_back	O(log32 n) worst case	O(1) when the value is in an edge buffer.
append, prepend, concat	O(log32 (n + m)) worst case	Shares unchanged tree structure.
subvec	O(log32 n)	Shares complete internal subtrees.
of_list, of_array, to_list, to_array	O(n)	Converts every value once.
map, fold_left, fold_right, iter	O(n)	Visits every value once.
sort, sort_uniq	O(n log n)	Uses OCaml list sorting internally.

Development

Build the project and run the test suite with Dune:

dune build
dune runtest

Run the native benchmark with:

dune exec bin/benchmark.exe