luau-wasm

Luau packaged as a Python extension for Pyodide.

This project demonstrates publishing a WebAssembly wheel to PyPI. The wheel contains a compiled CPython extension module that embeds the Luau compiler and VM. In Pyodide 314, micropip can install that PyPI wheel directly in the browser.

Try the playground: https://simonw.github.io/lua-wasm/

Installation

In Pyodide:

import micropip

await micropip.install("luau-wasm")

import luau_wasm

print(luau_wasm.execute('print("Hello from Luau")'))

In JavaScript with Pyodide:

await pyodide.loadPackage("micropip");
await pyodide.runPythonAsync(`
import micropip
await micropip.install("luau-wasm")
import luau_wasm
`);

pyodide.globals.set("source", 'print("Hello from Luau")');
const output = pyodide.runPython("luau_wasm.execute(source)");

Python API

import luau_wasm

output = luau_wasm.execute("""
local name = "Luau"
print(`Hello from {name}`)
""")
assert output == "Hello from Luau\n"

execute(source) creates a fresh sandboxed Luau state, runs the source, captures print() output, and returns that output as a Python string.

Compile and runtime failures raise luau_wasm.LuauError:

try:
    luau_wasm.execute('error("boom")')
except luau_wasm.LuauError as ex:
    print(ex)

run is an alias for execute.

Building

This repository vendors the minimal Luau source needed by the extension in vendor/luau/.

To update the vendored Luau source:

scripts/vendor-luau.sh

To run native tests (which use a native build, not the WASM build):

uv run python -m pytest

To build the Pyodide WebAssembly wheel:

scripts/build-pyodide-wheel.sh

That runs:

uv run --with pyodide-build pyodide build .

The expected wheel target for Pyodide 314 / Python 3.14 is:

cp314-cp314-pyemscripten_2026_0_wasm32

To build using cibuildwheel:

CIBW_PLATFORM=pyodide uv run --with cibuildwheel cibuildwheel

Publishing

Pyodide 314 implements the standardized PyEmscripten platform tags described by PEP 783.

The GitHub Actions publish workflow builds the Pyodide wheel with cibuildwheel.

Development Notes

The extension is intentionally small:

• native/_luau.cpp provides the CPython wrapper and output capture.
• setup.py compiles Luau.Common, Luau.Ast, Luau.Bytecode, Luau.Compiler, and Luau.VM into the extension.
• docs/index.html is a GitHub Pages playground that loads Pyodide, installs luau-wasm from PyPI with micropip, and executes Luau code through Python.