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https://github.com/ocaml-wasm/wasm_of_ocaml
https://github.com/ocaml-wasm/wasm_of_ocaml
Last synced: 3 months ago
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- Host: GitHub
- URL: https://github.com/ocaml-wasm/wasm_of_ocaml
- Owner: ocaml-wasm
- License: other
- Created: 2023-03-28T13:49:04.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2024-10-29T11:52:07.000Z (3 months ago)
- Last Synced: 2024-10-29T12:16:25.163Z (3 months ago)
- Language: OCaml
- Size: 22.2 MB
- Stars: 244
- Watchers: 13
- Forks: 9
- Open Issues: 28
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGES.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
Awesome Lists containing this project
- awesome-ccamel - ocaml-wasm/wasm_of_ocaml - (OCaml)
README
# Wasm_of_ocaml
Wasm_of_ocaml is a fork of Js_of_ocaml which compiles OCaml bytecode to WebAssembly.
## Requirements
Wasm_of_ocaml relies on the Binaryen toolchain; currently, only versions [118](https://github.com/WebAssembly/binaryen/releases/tag/version_118) or greater are supported. Binaryen commands must be in the PATH for wasm_of_ocaml to function.
## Supported engines
The generated code works with Chrome 11.9, Node.js 22 and Firefox 122 (or more recent versions of these applications).
In particular, the output code requires the following [Wasm extensions](https://webassembly.org/roadmap/) to run:
- [the GC extension](https://github.com/WebAssembly/gc), including functional references and 31-bit integers
- [the tail-call extension](https://github.com/WebAssembly/tail-call/blob/main/proposals/tail-call/Overview.md)
- [the exception handling extension](https://github.com/WebAssembly/exception-handling/blob/master/proposals/exception-handling/Exceptions.md)
OCaml 5.x code using effect handlers can be compiled in two different ways:
One can enable the CPS transformation from `js_of_ocaml` by passing the
`--enable=effects` flag. Without the flag `wasm_of_ocaml` will instead emit code
utilizing
- [the JavaScript-Promise Integration extension](https://github.com/WebAssembly/js-promise-integration/blob/main/proposals/js-promise-integration/Overview.md)
## Installation
The following commands will perform a minimal installation:
```
git clone https://github.com/ocaml-wasm/wasm_of_ocaml
cd wasm_of_ocaml
opam pin add dune.3.13 https://github.com/ocaml-wasm/dune.git#wasm
opam pin add -n --with-version 5.3.0-wasm .
opam install wasm_of_ocaml-compiler
```
You may want to install additional packages. For instance:
```
opam install js_of_ocaml-ppx js_of_ocaml-lwt
```
## Usage
You can try compiling the program in `examples/cubes`. Your program must first be compiled using the OCaml bytecode compiler `ocamlc`. JavaScript bindings are provided by the `js_of_ocaml` package. The syntax extension is provided by `js_of_ocaml-ppx` package. Package `js_of_ocaml-lwt` provides Javascript specific Lwt functions.
```
ocamlfind ocamlc -package js_of_ocaml,js_of_ocaml-ppx,js_of_ocaml-lwt -linkpkg -o cubes.byte cubes.mli cubes.ml
```
Then, run the `wasm_of_ocaml` compiler to produce WebAssembly code:
```
wasm_of_ocaml cubes.byte
```
This outputs a file `cubes.js` which loads the WebAssembly code from file `cube.wasm`. For debugging, we currently also output the generated WebAssembly code in text file to `cube.wat`. Since Chrome does not allow loading from the filesystem, you need to serve the files using some Web server. For instance:
```
python3 -m http.server 8000 --directory .
```
As a larger example, you can try [CAMLBOY](https://github.com/linoscope/CAMLBOY). You need to install a forked version of [Brr](https://github.com/ocaml-wasm/brr/tree/wasm). Once the Js_of_ocaml UI is compiled (with `dune build --profile release`), you can generate WebAssembly code instead with the following command:
```
wasm_of_ocaml _build/default/bin/web/index.bc-for-jsoo
```
## Implementation status
A large part of the runtime is [implemented](https://github.com/ocaml-wasm/wasm_of_ocaml/issues/5). File-related functions and dynamic linking are not supported yet.
Separate compilation is not implemented yet.
## Compatibility with Js_of_ocaml
Since the value representation is different, some adaptations are necessary.
The most notable change is that, except for integers, OCaml numbers are no longer mapped to JavaScript numbers. So, explicit conversions `Js.to_float` and `Js.float` are now necessary to convert between OCaml floats and JavaScript numbers. The typing of JavaScript Typed Arrays has also been changed to deal with this.
Additionally, OCaml physical equality will not work properly on JavaScript objects (it compares boxed values instead of values themselves). You should use `Js.string_equals` instead.
Some forked versions of [Brr](https://github.com/ocaml-wasm/brr/tree/wasm) and
[Gen_js_api](https://github.com/ocaml-wasm/gen_js_api/tree/wasm) are compatible with Wasm_of_ocaml.