Fatou

A language server, formatter, and linter for Julia.

Quick start

1. Install the Fatou extension.
2. Open a Julia file (.jl).
3. The extension starts fatou lsp automatically.

By default, the extension uses a fatou binary that ships inside the extension (one platform-specific VSIX per OS/architecture), falling back to downloading a matching binary from GitHub releases when none is bundled.

Features

• Starts fatou lsp automatically when you open Julia files.
• Formats Julia code using Fatou's deterministic formatter.
• Surfaces Fatou diagnostics in the editor.
• Registers itself as the default formatter for [julia] files.

Commands

• Fatou: Restart Server: stops and restarts the Fatou language server (re-reads settings and re-resolves the binary). Useful if the LSP gets wedged or after changing settings such as fatou.version or fatou.executablePath.

Binary installation

By default, the extension uses a fatou binary that ships inside the extension itself (one platform-specific VSIX per OS/architecture). No download, no GitHub round-trip, and the language server starts on first activation even on restricted or offline networks. Behavior is controlled by fatou.executableStrategy:

• bundled (default): use the binary that ships inside the extension. If you're on a platform without a platform-specific build (or you've installed the universal VSIX), the extension falls back to downloading a matching binary from GitHub releases.
• environment: look for fatou on the system PATH.
• path: use the binary at fatou.executablePath.

If you set fatou.version or fatou.releaseTag explicitly, the bundled binary is skipped and the requested version is downloaded from GitHub. When fatou.version is latest, the extension selects the most recent stable release that contains a matching platform asset.

Common setup examples

Use a local binary at a fixed path:

{
  "fatou.executableStrategy": "path",
  "fatou.executablePath": "/usr/local/bin/fatou"
}

Use whatever fatou is on your PATH:

{
  "fatou.executableStrategy": "environment"
}

Pin to a specific release:

{
  "fatou.version": "0.2.0",
  "fatou.githubRepo": "jolars/fatou"
}

Use fatou.releaseTag only if you need an exact tag override:

{
  "fatou.releaseTag": "v0.2.0"
}

Requirements and troubleshooting

• NixOS: the bundled binary won't run because of the dynamic loader path. The extension detects NixOS and skips the download, using fatou on your PATH instead; install fatou and set fatou.executableStrategy to environment, or use path with fatou.executablePath.
• Offline/restricted networks/proxies: the bundled-binary default works without network access. Only the explicit-version download paths (fatou.version/fatou.releaseTag) require GitHub connectivity.
• If a download fall-through fails, the extension shows a warning and falls back to looking up fatou on the system PATH.

Settings

Fatou registers itself as the default formatter for [julia] files.

• fatou.executableStrategy: how to locate the fatou binary: bundled (default), environment, or path.
• fatou.executablePath: path to the binary, used only when executableStrategy is path.
• fatou.version: version to install (default: "latest").
• fatou.releaseTag: advanced exact tag override (takes precedence if explicitly set).
• fatou.githubRepo: GitHub repo for downloads (default: "jolars/fatou").
• fatou.serverArgs: extra args after fatou lsp.
• fatou.serverEnv: extra environment variables.
• fatou.extraPath: extra PATH entries prepended for the language server process.
• fatou.logLevel: log level for the language server, mapped to RUST_LOG (off, error, warn, info, debug, trace; unset by default). fatou.serverEnv.RUST_LOG overrides this if both are set.
• fatou.trace.server: LSP trace level (off, messages, verbose).

Security and trust

When fatou.executableStrategy is bundled (the default), the extension prefers the binary that shipped inside the VSIX. If no bundled binary is available, or fatou.version/fatou.releaseTag is set explicitly, it downloads from GitHub releases configured by fatou.githubRepo (default jolars/fatou).