Editor support

Axle ships a language server (axle-lsp) and an official VS Code extension. Together they give you syntax highlighting, type-aware hover, goto-definition, find references, rename, contextual completion, inline diagnostics, code actions, and one-click axle build / axle run tasks.

Any editor that speaks the Language Server Protocol can drive axle-lsp directly — VS Code is the one with the polished client.

VS Code

Install

1. Install the axle compiler — see Install the compiler. The axle-lsp binary ships in the same package, next to axle.
2. Install the extension from the VS Code Marketplace (search for “Axle”) or sideload a .vsix built from source.

Once both pieces are in place, opening any .axle file activates the extension automatically. The status bar in the bottom-left shows the server state:

What you get

Settings

All keys live under the axle.* prefix in your settings.json.

Server lifecycle (changes restart the server) :

Live filters (applied without restart) :

Toggled at extension start :

Customising colours

The extension ships defaults that work with VS Code’s built-in Dark+ and Light+ themes. To override the colour of any token type (in any theme), add to your settings.json:

"editor.semanticTokenColorCustomizations": {
    "rules": {
        "class:axle":      { "foreground": "#FFD580", "bold": true },
        "interface:axle":  { "foreground": "#C9A0DC", "italic": true },
        "enum:axle":       { "foreground": "#A8E6CF" },
        "enumMember:axle": { "foreground": "#FFB6C1" },
        "namespace:axle":  { "foreground": "#87CEEB" }
    }
}

Every token type you can target, scoped to Axle with :axle : namespace, class, interface, enum, enumMember, type, typeParameter, function, method, parameter, variable, property, keyword, string, number.

Tasks

Ctrl+Shift+P → "Tasks: Run Task" lists five tasks under the axle provider:

You can also write project-local tasks in tasks.json:

{
    "type": "axle",
    "command": "build",
    "args": ["-O", "3"],
    "file": "${workspaceFolder}/src/main.axle",
    "label": "axle: release build"
}

The axle binary is resolved as the sibling of axle.server.path (the apt / Docker packaging ships them together) or falls back to bare axle on PATH.

Snippets

Type the prefix and hit Tab. The most-used ones:

Other editors

Any LSP-aware editor can drive axle-lsp directly. The general recipe is:

1. Make sure axle-lsp is on your PATH (it ships with axle).
2. Configure the editor to launch axle-lsp on stdio for files whose extension is .axle or whose language id is axle.

The protocol speaks plain LSP — no custom extensions, no proprietary methods. Semantic-token rendering depends on the editor mapping the 15 token types the server advertises (namespace, class, interface, enum, enumMember, type, typeParameter, function, method, parameter, variable, property, keyword, string, number) to its theme. The VS Code extension does this through semanticTokenScopes; other editors typically need a few lines of configuration to point each token type at the right theme colour.

A TextMate grammar ships with the VS Code extension as a syntax-only fallback for editors without an LSP client; it can be copied into any editor that consumes the TextMate format.

Known limitations

The language server is pre-1.0. A few rough edges :

• Semantic-token colours on non-ASCII lines. Highlighting may paint slightly shifted on a line containing multi-byte characters before the token. Diagnostics, hover and navigation are not affected.
• Rename targets. Methods, fields, and type names refuse the rename with an explanatory message — locals, parameters and free functions are the supported targets.
• Sibling edits propagate on save. Other project files are read from disk; an unsaved change in file B becomes visible to file A when B is saved.

See also

• Install the compiler — get axle + axle-lsp on your machine.
• Reading compiler errors — what the inline diagnostics map to.
• Concept index — every keyword / type / annotation on one page.