MyLang for VS Code

Language Server (LSP) for the MyLang2 programming language (.ml).

Features

• Syntax Errors — detected by the language's actual Lexer/Parser (a simplified built-in syntax checker is used when the compiler is unavailable).
• Diagnostics — undefined identifiers, assignments to as const / as readonly, duplicate declarations, nonexistent module members (strings.splitt → "Did you mean split?"), unknown modules, unused var declarations, and unused imports.
• Autocompletion — module members, structures, enums, this, results returned by http.Server(), and ctx inside route handlers; keyword snippets; paths in import "…"; installed packages from .module (import "Owner:repo"), and automatic imports for built-in modules and installed packages.
• JSDoc Comments (/** ... */) — parameter descriptions and types, return values, examples, deprecated APIs, and tag suggestions triggered by @.
• Language Features — Hover documentation, signature help, Go to Definition (including cross-file navigation through import "./file.ml"), Find All References, Rename Symbol, Document Outline, Workspace Symbol Search, Code Folding, and Semantic Highlighting.
• Quick Fixes — add missing imports, fix typos, and remove unused imports.
• Commands — MyLang: Run Current File, Restart Language Server, and Show Language Server Status.

Installation and Setup

npm install            # Install vscode-languageclient (the only dependency)
# Press F5 in VS Code to launch the Extension Development Host
npm run package        # Build the .vsix extension package

Connect the compiler to enable accurate syntax error detection using the mylang.compiler.path setting.

Specify either the package directory or the path to dist/src/index.js after running npx tsc.

If no path is provided, the language server searches the following locations in order:

1. <workspace>/dist/src/index.js
2. <workspace>/node_modules/mylang2
3. The mylang2 package located next to the extension.

Standard Library API

Autocompletion data for coreio, fs, net/http, and other standard modules is generated directly from the language's source code.

npm run gen:stdlib -- /path/to/LiveServer  # Overwrites server/data/stdlib.json

Run this command after making changes to library/.

Descriptions are extracted from JSDoc comments placed above classes or their call() methods.

JSDoc Support for Your Code

The extension recognizes JSDoc comments preceding func, struct, enum, and var declarations, as well as fields and methods.

Regular // and /* ... */ comments are still supported as plain descriptions.

/**
 * Returns the sum of two numbers.
 *
 * @param {number} a - The first operand.
 * @param {number} [b=1] - The second operand.
 * @returns {number} The sum of the numbers.
 * @example
 * add(5, 3)
 * @see sum
 */
func add(a, b = 1) {
  return a + b;
}

var answer = add(5, 3);

Hovering over add displays its description, parameters, @returns information, and example.

When typing add(, VS Code displays descriptions for individual arguments through Signature Help.

Hovering over a local parameter reveals its JSDoc type and description.

Inside /** ... */, typing @ triggers tag autocompletion, including @param suggestions populated with the function's actual parameter names.

Supported JSDoc Tags

The following tags are recognized:

• @param, @arg — parameter documentation.
• @returns, @return — return value documentation.
• @type — type information.
• @deprecated — marks deprecated APIs.
• @example — usage examples.
• @throws — possible exceptions.
• @see — references to related symbols.

Other tags are also preserved and displayed in Hover documentation.

Multiline tag descriptions are supported.

Note: JSDoc types are used exclusively for documentation and editor assistance. They do not modify type checking or interpreter behavior.

Configuration

See the MyLang section in VS Code settings.

Available settings include:

• mylang.compiler.path — path to the MyLang compiler.
• mylang.executable — path to the MyLang executable.
• mylang.diagnostics.* — diagnostic configuration options.
• mylang.completion.autoImport — automatic import suggestions.
• mylang.globals — names defined in initScript that should not be reported as undefined identifiers.

Tests

node test/run.js [path/to/dist/src/index.js]

This command starts the actual language server and verifies its functionality through the Language Server Protocol (LSP).

Tests cover JSDoc parsing, Hover documentation, signature help, argument descriptions, tag autocompletion, and other language server features.