benrbray / ghc-wasm-example

ghc-wasm-example

A working example demonstrating the use of:

• ghc-wasm-meta for compiling Haskell code to a WASI module
• browser-wasi-shim for running the compiled WASI module in the browser

At the moment, the build is based mostly on Brandon Chinn's fourmolu-wasm setup, in addition to the following resources:

• Haskell Discourse, "Javascript & WebAssembly backend"
• ghc-wasm-meta @ GitLab, Issue #1, "Allow disabling head.hackage in setup.sh" (and this commit, this workflow)
• ezyang 2011, "Accessing lazy structures from C"

Setup

Install ghc-wasm-meta according to the "Getting Started without Nix". I am using FLAVOUR=9.8. Then, populate your environment with source ~/.ghc-wasm/env.

$ wasm32-wasi-ghc --version
The Glorious Glasgow Haskell Compilation System, version 9.8.0.20230809

$ wasm32-wasi-cabal --version
cabal-install version 3.10.1.0
compiled using version 3.10.1.0 of the Cabal library

Next, follow the instructions to set up head.hackage, which allows Hackage packages to be used with GHC prereleases (such as ghc-wasm).

Build

The build scripts are organized as a justfile.

just build-wasm

Once the Haskell project has been built, you can run the frontend in development mode with:

cd frontend
npm run dev