Teal

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.

Introduction

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:

• Minimalism versus types (2019)
• Minimalistic typed Lua is here (2020)
• What's next for Teal (2021)

And here's an update from early 2024, describing the process that eventually resulted in Teal Spring '24, later in the year:

• Five years of Teal: minimalism versus growth in language design (2024)

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

Installing

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.

Binaries

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.

Running

Using the compiler directly

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

• tl run script.tl will run a Teal script.
• tl check module.tl will type check a Teal module, report any errors and quit.
• tl gen module.tl will check for syntax errors and generate a module.lua file in plain Lua with all type annotations stripped.
• 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.

Building projects with Cyan

To build whole projects, you probably won't want to run tl on each file individually. We recommend using Cyan, the build tool designed for Teal.

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")
tl.loader()

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

Documentation

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 https://github.com/teal-language/teal-types — 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.

Community

• Join the chat on Gitter!
  • You can also join via Matrix at #teal-language_community:gitter.im

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

License

License is MIT, the same as Lua.