helix-plus/book/src/guides/adding_languages.md

Adding new languages to Helix

In order to add a new language to Helix, you will need to follow the steps below.

Language configuration

1. Add a new [[language]] entry in the languages.toml file and provide the necessary configuration for the new language. For more information on language configuration, refer to the language configuration section of the documentation.
2. If you are adding a new language or updating an existing language server configuration, run the command cargo xtask docgen to update the Language Support documentation.

💡 If you are adding a new Language Server configuration, make sure to update the Language Server Wiki with the installation instructions.

Grammar configuration

1. If a tree-sitter grammar is available for the new language, add a new [[grammar]] entry to the languages.toml file.
2. If you are testing the grammar locally, you can use the source.path key with an absolute path to the grammar. However, before submitting a pull request, make sure to switch to using source.git.

Queries

1. In order to provide syntax highlighting and indentation for the new language, you will need to add queries.
2. Create a new directory for the language with the path runtime/queries/<name>/.
3. Refer to the tree-sitter website for more information on writing queries.

💡 In Helix, the first matching query takes precedence when evaluating queries, which is different from other editors such as Neovim where the last matching query supersedes the ones before it. See this issue for an example.

Common issues

• If you encounter errors when running Helix after switching branches, you may need to update the tree-sitter grammars. Run the command hx --grammar fetch to fetch the grammars and hx --grammar build to build any out-of-date grammars.
• If a parser is causing a segfault, or you want to remove it, make sure to remove the compiled parser located at runtime/grammars/<name>.so.