Runic on Save

Formats Julia files with Runic.jl every time you save them.

Installing the extension registers Runic as a Julia formatter and sets these defaults for Julia files:

"[julia]": {
    "editor.defaultFormatter": "JashAmbaliya.runic-on-save",
    "editor.formatOnSave": true
}

"Format Document" and "Format Selection" use Runic too. Formatting a selection runs runic --lines.

Requirements

Runic.jl must be installed. Either of these works:

# Recommended by Runic: a shared environment named @runic
julia --project=@runic -e 'using Pkg; Pkg.add("Runic")'

# Or, on Julia 1.12+, as a Pkg app (installs ~/.julia/bin/runic)
julia -e 'using Pkg; Pkg.Apps.add("Runic")'

The extension looks for Runic in this order:

1. runic.executablePath, if set.
2. A runic executable on PATH or in ~/.julia/bin.
3. Julia (runic.juliaExecutablePath, then julia.executablePath, then julia on PATH or in ~/.juliaup/bin), run as julia --project=@runic -e 'using Runic; exit(Runic.main(ARGS))'.

If Runic.jl isn't installed in the Julia project, the error notification has an Install Runic.jl button that runs the install command above in a terminal.

Settings

To keep Runic as the formatter but stop formatting on save:

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

When something goes wrong

• A file with a syntax error is saved unchanged. The status bar shows the line and column of the error.
• Runic is not found or fails triggers one error notification per session. Details are in Runic: Show Log (the "Runic" output channel), which also records the command used and how long each format took.
• The Runic item in the language status area (the {} next to "Julia" in the status bar) shows whether Runic is the default formatter, whether format on save is on, and the last error for the current file.
• Nothing happens on save? Check whether another formatter is set in your user settings ("[julia]": { "editor.defaultFormatter": ... }). VS Code also skips format on save when files.autoSave is afterDelay.

Development

npm install
npm run compile            # or: npm run watch
npm run test:unit          # needs Runic installed
npm run test:integration   # starts a separate VS Code instance with only this extension
npm run package            # builds runic-on-save-<version>.vsix
code --install-extension runic-on-save-<version>.vsix

Press F5 in VS Code to start an Extension Development Host with the extension loaded.

npm run test:integration downloads VS Code into .vscode-test/. To use an installed copy instead, set VSCODE_EXECUTABLE_PATH, for example to /Applications/Visual Studio Code.app/Contents/MacOS/Code. When running from a terminal inside VS Code, unset ELECTRON_RUN_AS_NODE first.

The extension ID is JashAmbaliya.runic-on-save. If you change publisher in package.json, update the ID in configurationDefaults, src/extension.ts and src/test/integration/suite.ts to match.