zig-lox

A bytecode interpreter for the Lox language from Crafting Interpreters implemented in Zig.

Dependencies

Building zig-lox requires Zig 0.9. Zig binaries are available through several package managers, or from zig's download page.

Usage

REPL:

zig run src/main.zig

Executing a file:

zig run src/main.zig -- examples/arithmetic.lox

Running tests

To run tests, run

make test

This runs the tests from the book using a test harness written in Zig. Note that test/for/closure_in_body.lox is currently skipped because closuring the induction variable of a loop works differently in zig-lox than in clox.

Building

Running make creates a debug build of zig-lox at bin/lox.

To create a release build, run make release.

Web Assembly

zig-lox can be compiled to a freestanding Web Assembly (WASM) library to run in a web browser or in node. Running

make wasm

will create a build at build/wasm-lib.wasm. An example of using the WASM library through node is provided in js/main.js. Similarly to the lox binary, this provides a REPL through

node js/main.js

and can execute a specified lox source file, for example:

node js/main.js examples/arithmetic.lox

Web REPL

A simple web REPL powered by the WASM library is available in the www directory. Try it live.

To run the web REPL locally, run

make www-server

(note, requires Python 3 to be available), and visit localhost:8000.

Experimental WASI build

It is also possible to produce a build targeting the WebAssembly System Interface. Running

make wasi

will create a build at build/lox-repl.wasm, which can be run using Wasmer like this:

wasmer run build/lox-repl.wasm

So far, only the REPL is supported in the WASI build--executing a source file is not yet possible.

This Lox REPL is also available as the wapm package jwmerrill/lox-repl. You can try it online at webassembly.sh by installing it

wapm install jwmerrill/lox-repl

and then running

lox-repl

Note: right now this only seems to work well in Chrome.

Status

Complete.

References

Crafting Interpreters source code

I've taken a lot of inspiration from zox, an earlier Zig implementation.