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Saule
stable26.30
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Editor Support

Every editor plugin is a thin client. The intelligence lives in saule-lsp, a Language Server Protocol implementation that ships with the toolchain, so all three editors get the same feature set:

  • Diagnostics — lex, parse, semantic, and type errors, live on every edit
  • Hover — types and signatures for locals, functions, methods, classes, enums, and stdlib members, with generic substitution
  • 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
  • Formatting — full-document and range formatting

Each plugin lives in its own repository:

Editor Repository
VS Code lauriszz123/saule-vscode
Neovim lauriszz123/saule-nvim
IntelliJ IDEA lauriszz123/saule-intellij

Install the server first

Section titled “Install the server first”

All three plugins need the binary, and the installer puts it on your PATH along with the saule CLI:

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

Plugins find it on your PATH, then in ~/.saule/bin. They do not run a binary from the project you open, because a repository can contain a target/debug/saule-lsp of its own. If you work on Saule itself and want your own build, turn on the setting for it: saule.allowProjectBuild in VS Code, vim.g.saule_use_project_build = true in Neovim, or Run the binaries from a project’s own target/ folder in IntelliJ.

Syntax highlighting and indentation are client-side, so they work even without the server. Everything in the list above does not.

VS Code

Section titled “VS Code”
Install in VS CodeView Saule on Visual Studio Marketplace

Or search for Saule in the Extensions view, or install it from a terminal:

Terminal window
code --install-extension saule.saule

Settings

Section titled “Settings”
Setting Default Purpose
saule.server.path "" Absolute path to saule-lsp. Empty means auto-detect.
saule.cli.path "" Absolute path to saule, used by the run commands. Empty means auto-detect.
saule.toolchainDir "" Directory holding both binaries, used when no explicit path is set.
saule.allowProjectBuild false Use a project’s own target/ build. Opening a folder then runs any target/debug/saule-lsp it contains, so this is only for working on Saule itself.
saule.server.extraArgs [] Extra CLI arguments for the server.
saule.trace.server "off" LSP message tracing — off, messages, or verbose.

Commands

Section titled “Commands”
  • Saule: Run File / Saule: Run Project — saule run on the active file or 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.

Neovim

Section titled “Neovim”

The repository is a plugin root, so any plugin manager installs it directly. With lazy.nvim:

return {
  { "lauriszz123/saule-nvim", ft = "saule" },
}

Then enable the language server. On Neovim 0.11+ the bundled lsp/saule.lua definition is picked up from the runtimepath:

vim.lsp.enable("saule")

With nvim-lspconfig (including NvChad), register it through the helper instead, which picks up your shared on_attach and capabilities:

require("saule.lsp").setup()

Either way the server is found on $PATH or in ~/.saule/bin, which the installer covers. vim.g.saule_lsp_path overrides it.

IntelliJ IDEA

Section titled “IntelliJ IDEA”

Works in Community and Ultimate (and other JetBrains IDEs) — it rides on the open-source LSP4IJ client rather than the Ultimate-only native LSP API.

View Saule on JetBrains Marketplace

Or install it from inside the IDE: Settings ▸ Plugins ▸ Marketplace, then search for Saule. The IDE offers to install LSP4IJ along with it.

Beyond the shared LSP features it adds:

  • File ▸ New ▸ Project… ▸ Saule — scaffolds exactly what saule init produces.
  • Run configurations — the gutter icon on any .sau file runs the project if the file sits inside a saule.config tree, and the single file otherwise.

Colouring, brace matching, and indent-while-typing come from a native IntelliJ lexer rather than the server, so they stay responsive.

Syntax highlighting

Section titled “Syntax highlighting”

The TextMate grammar is written once, in the language repository at grammar/saule.tmLanguage.json, next to the lexer it has to agree with. This site reads it at build time, and the VS Code extension ships a copy that npm run sync:grammar refreshes — so a keyword added in one place shows up everywhere.