Saule for VS Code

Full language support for .sau files: a TextMate grammar for syntax highlighting plus a Language Server Protocol client that talks to saule-lsp, the language server of the Saule programming language.

Features

Powered by the saule-lsp server:

• Diagnostics — lex, parse, semantic, and type errors, live on every edit.
• Hover — types and signatures for locals, functions, methods, classes, enums, and stdlib/native members (with generic substitution, so Table.remove(table<integer>) shows integer?).
• Go-to-definition and find-all-references.
• Document highlights and document symbols (outline / breadcrumbs).
• Inlay hints — inferred local types and parameter-name labels.
• Signature help — parameter popups while typing call arguments, and whenever the caret moves back inside a call's parens.
• Formatting — full-document and range formatting.

Provided by the extension itself, so they work with or without the server:

• Indentation while typing — Enter indents the new line, and block-closing keywords dedent as you finish them: end, until, else, elseif, catch and case snap to the right level. Saule closes blocks with words rather than braces, so there is no } for the usual dedent to hook onto. Driven by editor.formatOnType, which this extension turns on for .sau files (along with two-space indentation, matching saule fmt).
• Run commands — run the current file or the whole project in a terminal.

Install

Search for Saule in the Extensions view, install it from the Marketplace, or run:

code --install-extension saule.saule

The extension also needs the Saule toolchain, once per machine.

Install the toolchain (one time)

The extension needs the saule-lsp binary. The installer puts it, and the saule CLI, in ~/.saule/bin (%USERPROFILE%\.saule\bin) and adds that to your PATH:

irm https://lauriszz123.github.io/saule/install.ps1 | iex

curl -fsSL https://lauriszz123.github.io/saule/install.sh | sh

The extension discovers the binaries in the same order as the IntelliJ plugin and the Neovim plugin:

1. SAULE_LSP_PATH / SAULE_PATH environment variables.
2. saule.server.path / saule.cli.path, or saule.toolchainDir, from your User settings. A project's .vscode/settings.json cannot set these.
3. Only with saule.allowProjectBuild on: Cargo build output, walking up from each workspace folder looking for target/release then target/debug.
4. saule-lsp / saule on your PATH.
5. ~/.saule/bin (or $SAULE_HOME/bin), where the installer puts them.

Step 3 is off by default because a repository can commit a target/debug/saule-lsp of its own, and opening a folder should not run it. Turn it on if you work on the language itself. The extension is also disabled in untrusted workspaces.

Versioning

The extension version tracks the toolchain it targets — <year>.<build>, the same number saule --version prints, plus a .0 because the Marketplace validates the manifest as strict semver. It has to be written into package.json and both places package-lock.json keeps it, so one script writes all three:

npm run stamp -- 26.8
npm run stamp -- 26.8 --check   # verify, change nothing

Run the stamp before vsce package, and --check in CI — it turns "bumped the manifest and forgot the lockfile" into a failed job rather than an npm ci that refuses to install.

Settings

The extension also sets editor.tabSize: 2, editor.insertSpaces: true, editor.formatOnType: true and editor.wordBasedSuggestions: "off" for [saule] files. The last one leaves completion to saule-lsp: VS Code's word-based provider otherwise scrapes identifiers out of the open document and offers them everywhere, including the declaration positions where the server deliberately stays quiet — so naming a new fn suggested every similar-looking word already in the file. These are defaults — your own settings still win.

Commands

• Saule: Run File — saule run <file> on the active buffer, saving it first. Also on the editor context menu.
• Saule: Run Project — saule run from the workspace root.
• Saule: Restart Language Server — relaunch the server (e.g. after a fresh cargo build).
• Saule: Show Language Server Output — open the server's output channel for logs and traces.

Editor parity

src/indent.ts is a port of the IntelliJ plugin's SauleIndentModel and shares its test corpus with the Neovim plugin's lua/saule/indent.lua. All three are derived from the printer in crates/saule-fmt/src/lib.rs in the language repository. The three clients live in separate repositories now, so changing one is a change to all three: update saule-intellij and saule-nvim alongside it and re-run every suite.

npm test

Syntax highlighting

syntaxes/saule.tmLanguage.json is a copy. The grammar is written once, in the language repository at grammar/saule.tmLanguage.json, next to the lexer it has to agree with, and is read from there by the documentation site as well. A .vsix has to carry the file it ships, so this repository keeps a copy and refreshes it after an upstream change:

npm run sync:grammar              # from github.com/lauriszz123/saule
npm run sync:grammar -- ../saule  # from a local checkout

Colours come from the user's active theme via these scopes: keyword.control, keyword.declaration, entity.name.type, entity.name.function, string.quoted.double, comment.line, constant.numeric, constant.language, variable.language.

Build from source

Only needed to work on the extension itself.

git clone https://github.com/lauriszz123/saule-vscode.git
cd saule-vscode
npm install
npm run compile

# then either press F5 / "Run Extension" from Run & Debug,
# or package and install:
npm install -g @vscode/vsce
vsce package
code --install-extension saule-<version>.vsix

For zero-build syntax-only dev, copy this folder into %USERPROFILE%\.vscode\extensions\saule\ and reload — but the LSP features need the compiled out/extension.js (npm run compile).

License

MIT — see LICENSE.