Cora Ruby Interpreter

This is a Ruby interpreter in Zig, written by various LLMs, ala Agentic Engineering.

This is my sandbox. I might try to make something better or faster or more flexible with it, but really I'm just having fun.

The goal is to get a working Ruby interpreter that can pass most or all of ruby/spec, to explore just-in-time compilation, and to possibly look into gradual typing or other enhancements.

Features

• Uses the Prism parser
• Bytecode compiler
• Stack VM
• Experimental JIT compiler using TinyCC
• Experimental App packaging into a single executable

What Works

Some gems that are known to work, though I haven't tested each thoroughly:

• rake
• rubygems and bundler
• psych and yaml
• rack and rackup
• webrick
• sinatra
• erb

Cora has over on 10,000 ruby specs passing, which by my math is about a third of the way to being a complete Ruby.

Prerequisites

To build Cora, you'll need:

• Zig 0.16.x
• GNU make
• a C toolchain
• autotools for the bundled Onigmo build, including autoreconf

If you have the Nix package manager, you can fetch all the dependencies easily with:

nix develop

If you have direnv, it will automatically load the dev shell when you cd into the cora directory.

Build

zig build

This installs the main CLI at:

build/bin/cora

To run:

build/bin/cora [flags] [filename]

Useful CLI flags:

• -e - run a code string
• --ast - dump the Prism AST
• --dump-bytecode - dump compiled bytecode
• --jit - enable the experimental TinyCC JIT (disabled by default)
• --dump-jit-source - dump generated TinyCC JIT C source when JIT is enabled

Package an Application

Package a Ruby application as a single executable with --pack:

build/bin/cora --pack -o my-app path/to/main.rb
./my-app [args]

Cora appends the application files to its own executable, then extracts them to a private temporary directory each time the packaged binary starts. The entrypoint's parent directory is packaged by default; use --pack-root DIR to choose a project root and .coraignore to exclude exact file paths or directory prefixes.

Debug Build

For local development with full safety checks and debug info, build with:

zig build -Doptimize=Debug

ReleaseSafe is also available if you want runtime safety checks without the debug-build performance hit:

zig build -Doptimize=ReleaseSafe

TinyCC JIT

Enable the experimental TinyCC-based JIT compiler at runtime with --jit:

zig build -Doptimize=ReleaseFast
build/bin/cora --jit examples/fib.rb

Testing

Run the full Zig test suite:

zig build test

Run only matching tests:

zig build test -Dtest-filter="Proc"

Run matching tests and print each matched test name:

zig build test -Dtest-filter="Proc" -Dtest-verbose

Contributing

Go for it! LLM work welcome.

Copyright & License

Cora is copyright 2026, Tim Morgan. Cora is licensed under the MIT License; see the LICENSE file in this directory for the full text.

Some parts of this program are copied or vendored from other sources, and the copyright belongs to the respective owner. Such copyright notices are either at the top of the relevant file, in the same directory with a name like LICENSE, COPYING, or MIT.txt, or both.

file(s)	copyright	license
ext/dtoa.c	David M. Gay, Lucent Technologies	custom permissive
ext/cgi/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/csv/*	James Edward Gray II, Yukihiro Matsumoto, SHIBATA Hiroshi, and contributors	Ruby license / 2-clause BSD
ext/delegate/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/erb/*	Masatoshi SEKI and Ruby contributors	Ruby license / 2-clause BSD
ext/forwardable/*	Keiju ISHITSUKA, Daniel J. Berger, Ruby contributors	Ruby license / 2-clause BSD
ext/json/*	Florian Frank, Yukihiro Matsumoto, and Ruby contributors	Ruby license / 2-clause BSD
lib/stdlib/fileutils.rb	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
lib/stdlib/mkmf.rb	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
lib/stdlib/monitor.rb	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
lib/stdlib/pathname.rb	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
lib/stdlib/random/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
lib/stdlib/securerandom.rb	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/open3/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/onigmo/*	K. Kosako, K. Takata, Yukihiro Matsumoto	BSD-style / Ruby BSDL
ext/prism/*, ext/prism-templates/*	Shopify Inc.	MIT
ext/tinycc/*	Fabrice Bellard and TinyCC contributors	LGPL 2.1
ext/logger/*	Yukihiro Matsumoto	Ruby license / 2-clause BSD
ext/optparse/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/psych/*	Aaron Patterson, SHIBATA Hiroshi, Charles Oliver Nutter, and contributors	MIT
ext/rubygems/*	Chad Fowler, Rich Kilmer, Jim Weirich, and others	RubyGems license / MIT
ext/singleton/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/tempfile/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/timeout/*	Network Applied Communication Laboratory, Inc., IPA Japan, and Ruby contributors	Ruby license / 2-clause BSD
ext/tmpdir/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/shellwords/*	Akinori MUSHA and Ruby contributors	Ruby license / 2-clause BSD
ext/uri/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/webrick/*	Yukihiro Matsumoto and Ruby contributors	Ruby license / 2-clause BSD
ext/yaml/*	Aaron Patterson, SHIBATA Hiroshi, and Ruby contributors	Ruby license / 2-clause BSD

See each file/directory for the full copyright and license terms.