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This is the repository of tl, the compiler for Teal, a typed dialect of Lua.

The core compiler has no dependencies and is implemented as a single tl.lua file which you can load into your projects. Running tl.loader() will add Teal support to your package loader, meaning that require() will be able to run .tl files.


Here are videos of talks given at FOSDEM 2019, 2020 and 2021 which discuss the history of Lua and types, outline the motivations behind Teal and talk about the project's progress:

Check also the tutorial to get started with an overview of the language.


Via LuaRocks

Install Lua and LuaRocks, then run:

luarocks install tl

This should put a tl command in your $PATH (run eval $(luarocks path) if the LuaRocks-installed binaries are not in your $PATH).

Teal works with Lua 5.1-5.4, including LuaJIT.


Alternatively, you can find pre-compiled binaries for Linux x86_64 and Windows x86_64 at the releases page. The packages contain a stand-alone executable that can run Teal programs (without the need of a separate Lua installation) and also compile them to Lua.

Try it from your browser

You can give Teal a try directly from your browser with the Teal Playground! It compiles Teal into Lua using Fengari, a Lua VM implemented in JavaScript, so everything runs on the client.


Once tl is in your path, there are a few subcommands:

  • tl run will run a Teal script.
  • tl check will type check a Teal module, report any errors and quit.
  • tl gen will check for syntax errors and generate a module.lua file in plain Lua with all type annotations stripped.
  • tl build will compile your project via the rules defined in tlconfig.lua.
  • tl warnings will list all warnings the compiler can generate.

tl also supports some compiler options. These can either be specified on the command line or inside a tlconfig.lua file at the root of your project.

Loading Teal code from Lua

You can either pre-compile your .tl files into .lua, or you can add the tl.lua module into your project and activate the Teal package loader:

local tl = require("tl")

Once the package loader is activated, your require() calls can load and compile .tl files on-the-fly.


You can learn more about programming and using Teal in the docs/ folder. The tutorial is a great place to start!

Type definitions

tl supports declaration files, which can be used to annotate the types of third-party Lua libraries.

We have a collaborative repository for declaration files at — check it out and make your contribution!

Text editor support

Teal language support is currently available for Vim, Visual Studio Code and lite with linter support.


Teal is a project started by Hisham Muhammad, developed by a growing number of contributors and is written using Teal itself!


License is MIT, the same as Lua.