Release 23.10 Highlights

The Helix 23.10 release is finally here! 23.10 introduces some very large internal changes that enable some powerful features. A very big thank you to everyone who made this release possible.

New to Helix? Helix is a modal text editor with built-in support for multiple selections, Language Server Protocol (LSP), tree-sitter, and experimental support for Debug Adapter Protocol (DAP).

Let's check out this release's highlights.

Multiple language servers

23.10 brings a big change to the way we handle language servers. Previously each language could only support one language server at a time but now you can configure multiple to work in tandem. For example you might use the TypeScript language server for JavaScript/TypeScript development and also configure efm-langserver for Prettier formatting and ESLint diagnostics. With the new support for multiple language servers, you can specify which features to use from each language server.

This brings a big change to the way language servers are configured in your language configuration (languages.toml). All language servers are now specified separately from languages and then each language selects which language server(s) to use. From the example above, you might configure efm- langserver and typescript-language-server like so:

[language-server.efm]
command = "efm-langserver"
config.documentFormatting = true

[language-server.typescript-language-server]
command = "typescript-language-server"
args = ["--stdio"]
config.hostInfo = "helix"

[[language]]
name = "typescript"
auto-format = true
language-servers = [
  { name = "efm", only-features = ["format", "diagnostics"] },
  { name = "typescript-language-server", except-features = ["format", "diagnostics"] },
]

See more details in the language configuration docs.

Fuzzy matching with Nucleo

Helix uses "fuzzy" matching to filter as-you-type in components like the file picker. Previously we used the popular skim/fuzzy-matcher crates but in the 23.10 release we've switched to the new nucleo crate. Nucleo is significantly faster than skim and fzf, handles Unicode correctly, and uses a bonus system that feels more intuitive.

Nucleo also enables us to lazily stream in new items, which is a big boost for the user experience for pickers. In the asciicast above I'm scanning through my computer's /nix/store, a huge directory containing more than twenty million files. The file picker now works gradually as we scan through the directory and matches files as we find them.

Nucleo also paves the way for future picker upgrades. Stay tuned to the upcoming release notes to see where we'll take the picker.

Smart tab

Smart tab is a new feature bound to the tab key in the default keymap. When you press tab and the line to the left of the cursor isn't all whitespace, the cursor will jump to the end of the syntax tree's parent node. For example:

{
  key = "value";
  nested = {
    key2 = "value2"; # When the cursor is at the end of the line here, <tab>
                     # jumps right after the closing brace on the next line.
  };
}

This is useful in languages like Nix for adding semicolons at the end of an attribute set or jumping to the end of a block in a C-like language:

Expanded support for registers

Registers allow you to save and paste values. For example you might select a paragraph, use "ay to yank it into the a register, and later use "ap to paste that paragraph. Some registers have special effects when read or written to though like the _ "blackhole" register: any values written are discarded and nothing can be read. Special registers have been expanded to include some useful ones from Kakoune and clipboard registers:

• %: the current buffer name
• #: the number of each selection, 1-indexed
• .: the contents of each selection
• * and +: system and primary clipboards

Also check out the new register statusline element. It appears when you select a register with ". Notice the reg=# in the bottom-right corner of the statusline in the asciicast when we select the # register and how it goes away when we paste that register (p) or increment the selections (C-a).

Initial support for LSP DidChangeWatchedFiles

Some language servers use the DidChangeWatchedFiles notification to discover changes to related files in other languages. For example, rust-analyzer will fetch and index new dependencies when you add them to your Cargo.toml. Helix will now send file change notifications when the file is changed by Helix itself. Full support for DidChangeWatchedFiles will require a file watcher but for now we're able to support the most common use-case for DidChangeWatchedFiles.

Syntax highlight regex prompts

Regex prompts like those created with s, S or | are now syntax highlighted via tree-sitter-regex. The highlighting makes special characters more obvious and can catch syntax errors like trailing backslashes.

Wrapping up

As always, this is just the tip of the iceberg for the 23.10 release. Check out the changelog for the full details.

Come chat about usage and development questions in the Matrix space and follow along with Helix's development in the GitHub repository.