MoonBit Navigator

VS Code extension that enables "Go to Definition" (F12) for MoonBit imports in JavaScript/TypeScript files.

What is this for?

This extension is designed to work with @mizchi/vite-plugin-moonbit, a Vite plugin that enables seamless integration between MoonBit and JavaScript/TypeScript projects.

When using vite-plugin-moonbit, you can import MoonBit modules using the mbt: prefix:

import { greet } from "mbt:myproject/lib";

However, VS Code cannot resolve these virtual imports by default, breaking "Go to Definition" functionality. MoonBit Navigator solves this by mapping mbt: imports back to the actual .mbt source files.

Features

• Go to Definition: Navigate from mbt:project/package imports directly to MoonBit source files
• Symbol Navigation: Jump to specific pub fn, pub struct, pub enum, and pub type definitions
• Multi-file Support: Works across multiple .mbt files in a package
• Automatic Discovery: Automatically discovers moon.mod.json files in your workspace
• Cache Invalidation: Watches for changes to moon.mod.json files and updates automatically

Usage

1. Install the extension
2. Open a workspace containing MoonBit projects (with moon.mod.json files)
3. Open a JavaScript/TypeScript file with mbt: imports
4. Use F12 (Go to Definition) or Ctrl+Click on an import path

Supported Import Patterns

// Named imports - F12 on symbol jumps to its definition
import { greet, Point } from "mbt:myproject/lib";

// Namespace imports - F12 jumps to the first .mbt file
import * as lib from "mbt:myproject/lib";

// Dynamic imports
const pkg = await import("mbt:myproject/lib");

Requirements

• VS Code 1.85.0 or higher
• MoonBit project with moon.mod.json file

Configuration

Commands

Path Resolution

The extension supports two methods for resolving mbt: import paths:

1. moon.mod.json (Default)

Automatically discovers moon.mod.json files and uses the name field to match projects.

2. jsconfig.json / tsconfig.json paths

For projects using custom path mappings (e.g., with @aspect-build/aspect or @aspect-build/aspect), you can configure paths in your jsconfig.json or tsconfig.json:

{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "mbt:myproject/*": ["resources/moon/*"]
    }
  }
}

This is useful when:

• Your MoonBit source is in a subdirectory (e.g., resources/moon/)
• You're using a bundler like Vite with @mizchi/vite-plugin-moonbit
• The moon.mod.json name doesn't match your import pattern

How It Works

1. Import Detection: Parses mbt:{projectName}/{packageName} pattern from import statements
2. Project Resolution: First tries moon.mod.json, then falls back to jsconfig/tsconfig paths
3. Package Mapping: Locates the package directory based on the resolved path
4. Symbol Search: Scans .mbt files for public symbol definitions matching the imported name

Supported MoonBit Declarations

The extension recognizes the following public declarations:

pub fn function_name() -> Type { ... }
pub struct StructName { ... }
pub enum EnumName { ... }
pub type TypeAlias = Type

// Visibility modifiers are also supported
pub(all) fn public_all() -> Unit { ... }
pub(readonly) struct ReadOnly { ... }
pub(open) enum OpenEnum { ... }

[!NOTE] Currently, symbol detection uses regex-based parsing. This covers most common cases but may not handle complex or multi-line declarations. MoonBit LSP integration is planned for future versions to provide more accurate symbol resolution.

Development

# Install dependencies
npm install

# Compile
npm run compile

# Watch mode
npm run watch

# Run tests
npm run test

# Lint
npm run lint

# Package extension
npm run package

License

MIT