Teal

What is Teal?

Teal is a typed dialect of Lua. Teal's Github repository <https://github.com/teal-language/tl>_.

Teal compiles into Lua, so you can use it in any Lua 5.1+ runtime. If you are familiar with TypeScript, Teal is to Lua what TypeScript is to JavaScript. You can learn the syntax in the Teal book <https://teal-language.org/book/>_.

Teal's syntax is mostly the same as Lua, but with additional type declarations and annotations. It will help you catch many mistakes before even running a script, and provide confidence about large code changes.

Using the type checker

To compile your .tl files into .lua files, install Cyan, Teal's build system <https://github.com/teal-language/cyan>_.

Create a directory for your project, with a tlconfig.lua file inside. All of your scripts (i. e. the scripts directory) should be within this directory. tlconfig.lua configures the Teal build system and compiler, see the complete list here <https://teal-language.org/book/compiler_options.html>_.

.. note:: You can use cyan init to set up a directory for a Teal project automatically.

In addition to setting up a build process, you will need the declaration files for the OpenMW API <https://gitlab.com/OpenMW/openmw/-/jobs/artifacts/master/raw/teal_declarations.zip?job=Teal>_. Unpack them into a directory of your choice, and add that path to the include_dir option in your tlconfig.lua. Alternatively, you can add -I <my-dcelaration-directory-path> as an agument to Cyan commands.

After everything is ready, run cyan build in the same directory as tlconfig.lua. It will find all the .tl files in the source_dir, and put compiled .lua files at the same relative paths inside build_dir. Running cyan build will also perform a type check, notifying you of any mismatches or mistakes.

.. note:: source_dir and build_dir can be the same directory. In fact, that is the recommended arrangement, so that it's convenient to include the original sources with your scripts.

IDE support

Work on Teal Language Server <https://github.com/teal-language/teal-language-server>_ is still ongoing, so for now the only supported IDE is Visual Studio Code <https://code.visualstudio.com/>. It's available on Windows, Linux and Mac, so most likely you can run it too. Teal's extension can be found here: VSCode Marketplace <https://marketplace.visualstudio.com/items?itemName=pdesaulniers.vscode-teal> (or simply search for "Teal" in the extension UI).

.. note:: VSCode also has a web version, but the Teal extension isn't available there.