Adding languages

Language configuration

To add a new language, you need to add a language entry to the languages.toml found in the root of the repository; this languages.toml file is included at compilation time, and is distinct from the languages.toml file in the user's configuration directory.

[[language]]
name = "mylang"
scope = "scope.mylang"
injection-regex = "^mylang$"
file-types = ["mylang", "myl"]
comment-token = "#"
indent = { tab-width = 2, unit = "  " }

These are the available keys and descriptions for the file.

Grammar configuration

If a tree-sitter grammar is available for the language, add a new grammar entry to languages.toml.

[[grammar]]
name = "mylang"
source = { git = "https://github.com/example/mylang", rev = "a250c4582510ff34767ec3b7dcdd3c24e8c8aa68" }

Grammar configuration takes these keys:

Where source is a table with either these keys when using a grammar from a git repository:

Or a path key with an absolute path to a locally available grammar directory.

Queries

For a language to have syntax-highlighting and indentation among other things, you have to add queries. Add a directory for your language with the path runtime/queries/<name>/. The tree-sitter website gives more info on how to write queries.

NOTE: When evaluating queries, the first matching query takes precedence, which is different from other editors like neovim where the last matching query supersedes the ones before it. See this issue for an example.

Common Issues

• If you get errors when running after switching branches, you may have to update the tree-sitter grammars. Run hx --fetch-grammars to fetch the grammars and hx --build-grammars to build any out-of-date grammars.

• If a parser is segfaulting or you want to remove the parser, make sure to remove the compiled parser in runtime/grammar/<name>.so

• The indents query is indents.toml, not indents.scm. See this issue for more information.