dannywillems/web-ocaml-rust-tuto

List of tutorials/projects experiencing OCaml and Rust mixed code running together in the browser.

web-ocaml-rust-tuto

List of tutorials/projects experiencing OCaml and Rust mixed code running together in the browser.

Before starting, read the section about setting up the environment.

Idea

The general idea is to compile Rust into wasm and exporting some functions in JavaScript as a ES module. On the OCaml side, js_of_ocaml is used to compile OCaml code to JavaScript. The Caml code uses usual require function to use functions from the ES module generated by wasm-bindgen, and then get access to the Rust code. Exchanging values between OCaml and Rust must be performed very carefully. TODO: add link to the tutorials playing with values

Most of the tutorials will be focused on Caml calling Rust, and not the opposite. Webpack is then used to bundle the JavaScript generated by Caml and the ES module generated by wasm-binding, and potentially additional npm packages.

Notes

• wasm-pack build --target nodejs will build a ES module than can be used in NodeJS. Imagine you have a

use wasm_bindgen::prelude::*;

#[wasm_bindgen]
pub fn return_zero() -> u64 {
    0
}

built with wasm-pack build --target nodejs. You can after that use

node --experimental-modules --experimental-wasm-modules
> var t = require("./pkg/js_of_ruml.js")
> t.return_zero()

The default build target is bundler which requires a bundler (like webpack) afterwards.

• It looks like there are some issues related to wasm-opt (WASM optimizer) while building with wasm-pack. Adding these build options in the toml fix temporarily the issue

# https://github.com/rustwasm/wasm-pack/issues/886
[package.metadata.wasm-pack.profile.release]
wasm-opt = ["-O2", "--enable-mutable-globals"]

Rust

• wasm-pack: tools to get a workflow to build wasm code from Rust.
• rustwasm: book about Rust and WASM
• Awesome Rust/WASM: list of projects related to Rust/WASM interop

WASM

• wabt: toolset for wasm.
• binaryen: compiler toolchain for wasm.

Setup the environment

Rust

Install wasm-pack

curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh

NodeJS

To build the Rust code and use it in Node, install node using nvm, and install the latest Node version (nvm install 12.18.3 followed by nvm use 12.18.3).