Khora for Visual Studio Code

Official language support for Khora: errors as you type, types on hover, completion, navigation, refactorings, and formatting for .kh files.

Every feature except syntax colouring comes from the Khora compiler itself, through its built-in language server. What the editor shows is exactly what khora check reports, so the two can never disagree.

Getting started

1. Install Khora. Follow the instructions at khoralang.com. The installer puts khora on your PATH.
2. Install this extension from the Extensions view: search for Khora.
3. Open a folder with .kh files. The language server starts on its own. The status bar shows which Khora version is answering.

No other setup is needed.

Features

Errors and warnings as you type

Type errors, missing capabilities, unhandled errors and lint findings appear while you edit, with the same messages the command line gives. Lint levels from your project's khora.toml (including lint groups) are applied.

Hover

Hover over any name to see its type, and its documentation if it has any.

Inlay hints: what a call needs and what it can raise

Khora infers which capabilities a call uses and which errors it can raise. The extension shows both, in line, at each call where either one applies:

let answer = charge(account, amount);   // with { db: Db, clock: Clock } raises DbError

Calls that need nothing and can't fail get no hint, so the marked lines are the ones that cross a boundary. Inferred types are shown where the source doesn't already say them.

Completion and signature help

Completion for locals, fields, methods, modules and imports, and parameter hints as you type a call.

Navigation

• Go to Definition, Go to Type Definition and Go to Implementation
• Find All References, and highlighting of every use of the name under the cursor
• Rename across files
• Outline and breadcrumbs for the current file, and Go to Symbol in Workspace (Ctrl+T / Cmd+T)

Quick fixes and refactorings

Open the lightbulb (Ctrl+. / Cmd+.) for fixes from the diagnostic under the cursor, and for refactorings. A selection:

• add a missing import;
• add ! to a call that can raise, or add the error to the function's raises clause;
• handle a failure with catch, or turn it into a Result with attempt;
• add a raises or with clause, or an arm to a catch;
• write a call as a pipeline (|>), or a pipeline as a call;
• extract an expression into a let or a function, inline a binding, or lift a lambda into a function;
• invert an if, write an if as a match, or add an else branch;
• generate a test or a benchmark for a function;
• export a declaration with pub, or stop exporting it;
• start a documentation comment or an example block.

Run tests from the editor

Each test in a file gets a ▶ Run link above it, which runs that test with khora test.

Formatting

Format Document, and format on save for Khora files, using the same formatter as khora fmt. Formatting options come from your project's khora.toml.

Semantic highlighting

On top of the usual syntax colouring, the compiler tells the editor what each name is: a local, a parameter, an imported function, a type, a capability. So colour follows meaning, not just spelling.

Also

Code folding, smart selection expansion (Shift+Alt+→ / Ctrl+Shift+Cmd+→), bracket matching, comment toggling, and auto-closing pairs.

Toolchain versions

If a project pins a Khora version in khora.toml ([toolchain] version), the language server switches to that version automatically, just as the khora command does. The status bar shows the version in use; hover over it to see why that version was chosen.

The status bar item turns yellow when the project pins a version that isn't installed. Install it with khora toolchain install <version>.

Settings

Format on save is turned on for Khora files only. To turn it off:

"[khora]": {
  "editor.formatOnSave": false
}

Commands

Open the Command Palette (Ctrl+Shift+P / Cmd+Shift+P) and type Khora:

Troubleshooting

"could not start khora lsp": the extension couldn't find or run khora. Check that khora --version works in a terminal. If VS Code was open while you installed Khora, restart VS Code so it picks up the new PATH, or set khora.server.path to the full path of the executable.

No errors or hovers, only colours: the language server isn't running. Run Khora: Show Language Server Output to see why.

Settings in khora.toml don't take effect: a khora.toml that fails to load is shown as an error on the line to fix. Until it's fixed, the server uses default settings.

Upgrading from an extension older than 0.3.1: earlier versions were published as khora-lang.khora. Uninstall that one, or both will run.

Other editors

The language server works with any editor that speaks the Language Server Protocol: run khora lsp over standard input and output. See Editor setup.

Feedback

Report bugs and ask questions on GitHub. Khora is released under the MIT or Apache-2.0 licence, at your option.