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Fun

v0.1.1 · by omdxp · added 3 November 2026

Fun language support: syntax highlighting, outline, run buttons and the fls language server.

LanguagesLanguage servers
Install in Forge SuperView the source

How to install

With Forge Super installed, the button above opens the app on this extension, where you press Install. Nothing is installed until you do.

You can also open the Extensions panel in the app and search for Fun. The extension's id is fun-lang.

Don't have Forge Super yet? Download it here.

README

From the extension's repository, written by its authors and not by Mentenaz. See the source.

Fun for Zed

Language support for Fun in Zed.

  • Syntax highlighting, brackets, indents, outline and text objects, from the tree-sitter-fun grammar.
  • The fls language server: diagnostics, hover, completion, goto definition, formatting and references.
  • Gutter run buttons for main, test and fuzz blocks.

Language server

The extension looks for fls in this order:

  1. lsp.fls.binary.path in your Zed settings.
  2. fls on your PATH.
  3. The latest Fun release, downloaded on first use. It gives fls its own fun and standard library but does not put fun on your PATH, so install Fun for the run and test buttons.
{
  "lsp": {
    "fls": {
      "binary": { "path": "/path/to/fls" },
      "settings": {
        "fun_path": "/path/to/fun",
        "stdlib_dir": "/path/to/share/fun",
        "debug": false
      }
    }
  }
}

fun_path and stdlib_dir are optional and reach fls as FLS_FUN_PATH and FUN_STDLIB_DIR.

Run buttons

The extension ships tasks and tags the code they apply to, so Zed shows a run button in the gutter:

  • fun main: runs the file (fun -in <file>).
  • Each test "..." block: runs that one test.
  • Each fuzz "..." block: runs that fuzz target.

The same tasks, plus running the whole file's tests, running them with coverage and linting the file, are in the task picker (task: spawn). fun must be on your PATH.

Debugging

fun debug build (task picker) compiles the current file with debug info into fun-out/debug/fun-debug. Then start it under Zed's built-in CodeLLDB adapter with this .zed/debug.json:

[
  {
    "label": "Debug Fun file",
    "adapter": "CodeLLDB",
    "request": "launch",
    "program": "$ZED_WORKTREE_ROOT/fun-out/debug/fun-debug",
    "cwd": "$ZED_WORKTREE_ROOT",
    "build": "fun debug build"
  }
]

The build task uses cc, so it works on macOS and Linux. On Windows, build the file with fun -in <file> -g and point the scenario at the result.

Editor commands

Zed extensions cannot add commands. Use Zed's own: editor: restart language server and dev: open language server logs.

Not available in Zed

Zed has no Test Explorer or coverage API, so coverage shading and the Testing view exist only in the VS Code extension. Use the coverage task and read the printed percentage.

Develop

Open the command palette, run zed: install dev extension and pick this folder.