Release 22.03 Highlights

Ranging from small quality-of-life improvements and fixes to large features and refactors, Helix 22.03 brings some exciting changes. Helix is a modal text editor with built-in support for multiple selections, Language Server Protocol (LSP), tree-sitter, and now Debug Adapter Protocol (DAP).

Before we look at the highlights, there are some administrative notes. master branch changes are now published separately from the release documentation. Find the new master docs here. Helix is switching versioning schemes. Expect to find new releases in Calendar Version format: YY.0M(.MICRO). We're aiming to cut regular releases every two months or so. Check out the changelog for all of the new features and fixes from this release.

With that out of the way, let's check out the highlights!


Helix 22.03 brings a new CLI flag: hx --health. Use the new health-check flag to troubleshoot missing language servers and queries.

Check the health of all languages with hx --health or ask for details about a specific language with hx --health <lang>.

Experimental DAP Support

Debug Adapter Protocol (DAP) is an abstract protocol for editors and debuggers to communicate. It's very similar in spirit to the Language Server Protocol (LSP), but built for debugging. Interact with the debug adapter with <space-d>.

Note that the DAP adapter is experimental: it isn't yet documented, there may be bugs, and the UX is a bit clunky. Contributions are very welcome!

Incremental Injection Parsing Rewrite

One of the cooler features of syntax highlight driven by tree-sitter is the ability to inject a language into another language's document. For example, if you're writing Markdown, you might use a code-fence like so:

This is some rust:

println!("Hello, world!")

Helix highlights the Rust block by injecting tree-sitter-rust. Injections have been rewritten so that changes within are now parsed incrementally, which is a big speed boost when editing documents with large injected blocks.

Along with this rewrite, Helix now supports combined injections. For example, when highlighting Interactive Elixir (IEx), we might have a block of code like the following:

iex> send(self(), :hello)
iex> receive do: (:hello -> :ok)

The IEx grammar injects tree-sitter-elixir into each line after the prompt token. Combined injections cover the case where separate injected documents must be parsed in one combined document, like so:

iex> if true do
...>   :ok
...> end

Helix can now parse all three lines together. In the future this can be used to add support for templating languages like EJS or ERB.

Tree-Sitter Grammars Refactor

In the past, tree-sitter grammar repositories have been added to the Helix repository as Git submodules. Submodules can be painful to work with though, especially when there are more than 50 in a repository. Cloning, CI, and packaging times have slowed down as language support has improved.

Helix 22.03 completely overhauls the system for tree-sitter grammars. The headline is that submodules are gone! If you're working with the source, you can now clone with a standard git clone So where did the tree-sitter submodules go? They've been replaced with two new CLI flags: hx --grammar fetch to clone grammar repositories into the runtime directory and hx --grammar build to compile them. Use -g for short. Grammar repositories are shallow-cloned in parallel, so fetching all 60 grammars can now take as little as 6 seconds on a good connection.

If you're building from source or developing Helix, note that fetching and building are included in the helix-term build step, so you should not need to manually fetch or build grammars.

Additionally, if you would like to customize which tree-sitter grammars you fetch and build, you may now add the use-grammars key to the top of your languages.toml:

If you're writing a tree-sitter grammar, you can try out integrating it by pointing helix to your grammar's local path in languages.toml without needing to publish changes to a Git remote:

name = "mylang"
# ..

name = "mylang"
source = { path = "/local/path/to/tree-sitter-mylang" }

Running hx -g build will build the grammar. Add some queries and you're on your way to interactive grammar development.

Up Next

The next release is sure to be exciting as well. Contribute and follow along with development in the GitHub repository and be sure to join in on discussions in the Matrix channel.