Leo

Leo for Zed

A Zed extension for Leo and Aleo language support.

Features

• Syntax highlighting for Leo files.
• Syntax highlighting for Aleo files.
• Outline symbols for Leo programs, structs, records, mappings, functions, transitions, and tests.
• Runnable markers for Leo test functions annotated with @test.
• Leo snippets.
• Leo LSP integration through leo-lsp from PATH or a configured binary path.

Leo Tests

Zed currently requires a task template to bind runnable tags to commands. Add this once to your global Zed tasks.json:

[
  {
    "label": "leo test $ZED_CUSTOM_test",
    "command": "leo",
    "args": ["test", "$ZED_CUSTOM_test"],
    "cwd": "$ZED_WORKTREE_ROOT",
    "tags": ["leo-test"],
    "save": "all",
    "use_new_terminal": false,
    "allow_concurrent_runs": true
  }
]

After this is configured, Leo functions annotated with @test show a runnable marker in the editor gutter.

Tooling

The extension does not install Leo tooling. Install leo, leo-fmt, and leo-lsp separately, and make sure the commands are available on PATH.

If Zed cannot find leo-lsp on PATH, configure the binary in your Zed settings:

{
  "lsp": {
    "leo-lsp": {
      "binary": {
        "path": "/absolute/path/to/leo-lsp",
        "arguments": [],
        "env": {}
      }
    }
  }
}

The binary setting is optional. Use it only when the default leo-lsp lookup is not enough.

Formatting

leo-lsp 4.2.0 does not advertise LSP document formatting. leo-fmt currently formats files and directories in place. Zed external formatters must read source from stdin and write formatted source to stdout, so leo-fmt should not be configured as a Zed external formatter unless it gains stdin/stdout support.

To run leo-fmt manually from Zed, add a global task:

[
  {
    "label": "leo fmt current file",
    "command": "leo-fmt",
    "args": ["$ZED_FILE"],
    "cwd": "$ZED_WORKTREE_ROOT",
    "save": "current",
    "use_new_terminal": false,
    "allow_concurrent_runs": true
  }
]