MoonBit

MoonBit for Zed

Official MoonBit language support for the Zed editor.

This extension provides Tree-sitter-based syntax highlighting together with the native MoonBit Language Server (moon lsp).

---

Features

• Tree-sitter syntax highlighting
• Partial MoonBit 0.10.4 syntax support (literal Iterators and Bytes interpolation are locked by tree-sitter-moonbit current support)
• Native MoonBit LSP integration (moon lsp)
• Outline support
• Bracket matching
• Indentation support

---

Status

Functional and actively maintained.

The extension intentionally keeps its Rust implementation minimal and delegates language intelligence to the official MoonBit Language Server while following the upstream Tree-sitter grammar.

The extension tracks the upstream MoonBit Tree-sitter grammar and native MoonBit language server.

Syntax support is limited by the currently pinned upstream grammar revision and may not yet cover every feature introduced in the latest MoonBit release.

---

Requirements

• Zed Editor
• MoonBit 0.10.4 or newer

Verify your installation:

moon version

The language server is included with the MoonBit toolchain:

moon lsp

No separate npm package is required.

---

Installation (Development)

Clone the repository:

git clone https://github.com/quirk-lab/zed-moonbit
cd zed-moonbit

Then in Zed:

• Open the Command Palette
• Run:

zed: install dev extension

Official releases are available from:

https://github.com/quirk-lab/zed-moonbit/releases

---

Optional: associate moon.pkg with MoonBit

Since moon.pkg is a MoonBit package manifest rather than a source file, you may want to associate it manually:

{
  "file_types": {
    "MoonBit": ["moon.pkg"]
  }
}

Zed currently cannot associate languages with exact filenames automatically.

---

Development

Using Just:

just dev
just validate-queries
just test-syntax
just zed-log

Using Make:

make dev
make validate-queries
make test-syntax
make zed-log

Windows:

pwsh -File scripts/dev.ps1

---

Tree-sitter Development

Tree-sitter queries live in:

languages/moonbit/

Always validate queries after making changes:

just validate-queries

or

make validate-queries

Never guess node names.

---

Debugging

Print the Zed log path:

just zed-log-path

Tail logs:

just zed-log

If you encounter errors such as:

Invalid node type "..."

verify the syntax tree using:

tree-sitter parse example.mbt

and compare it with:

src/node-types.json

---

Project Structure

src/lib.rs              Rust extension entry point
extension.toml          Extension manifest
languages/moonbit/      Tree-sitter configuration and queries
scripts/                Development utilities

---

Design Principles

• Thin extension
• Native MoonBit tooling
• Upstream-first grammar
• Minimal, maintainable queries
• Validate before testing

---

Roadmap

• Improve query coverage
• Refine outline support
• Improve indentation rules
• Track new MoonBit language releases

---

Contributing

Small, focused pull requests are preferred.

Before opening a PR, always run:

just validate-queries

---

Troubleshooting

Error: failed to compile grammar 'moonbit'

This is usually caused by a corrupted local Tree-sitter grammar cache.

To fix:

1. Close Zed.
2. Delete the local grammars/moonbit directory (or the entire grammars directory).
3. Restart Zed.
4. Reinstall the extension.

This is a local cache issue rather than an extension bug.

---

License

MIT