Installation: Editors

Zed

The BAML extension for Zed provides syntax highlighting and language server support for editing BAML files.

Installation

  1. Open Zed
  2. Open the Extensions panel: Zed → Extensions (or press Cmd+Shift+X on macOS)
  3. Search for “baml”
  4. Click Install

The extension will automatically download and configure the BAML language server.

Features

FeatureSupported
Syntax highlighting for BAML files✅
Language Server Protocol (LSP) integration✅
Jump to definition✅
Error diagnostics✅
LLM playground (via browser)✅

Opening the BAML Playground

The BAML Playground runs as a local server and can be accessed via your browser:

  1. Open the Command Palette with Cmd+Shift+P (macOS) or Ctrl+Shift+P (Linux)
  2. Search for “open language server logs” and select dev: open language server logs
  3. In the LSP Logs panel, search for “Starting Playground server on”
  4. Copy the URL shown (e.g., 127.0.0.1:3704)
  5. Open that URL in your browser to access the playground

The playground server starts automatically when the BAML language server initializes. If you don’t see the message, try restarting the language server.

Why can’t I just click “Open Playground” like in VS Code?

In VS Code, Cursor, and JetBrains, you’ll see an “Open Playground” button above each BAML function. Unfortunately, Zed doesn’t yet support the LSP features needed to make this work:

Once Zed adds these features, the playground will be accessible with a single click. Until then, the LSP logs workaround above is the way to go. You can follow the linked GitHub issues to track progress.

How It Works

The Zed extension includes:

  • Tree-sitter grammar: Provides accurate syntax highlighting based on the BAML tree-sitter grammar
  • Language Server: Connects to the BAML Language Server for features like jump-to-definition, diagnostics, and more

Setting Environment Variables

You can set environment variables (like API keys) in the BAML Playground via your browser. Click on the Settings button in the playground to configure them.

Alternatively, you can set environment variables in your shell or through a .env file in your project root. The BAML language server will pick up variables from your environment.

Environment variables set in the playground are stored locally and persist between sessions.

Troubleshooting

Extension not appearing

Make sure you’re running a recent version of Zed. The BAML extension requires Zed’s extension system.

Language Server not starting

If the language server fails to start:

  1. Check the Zed logs for errors
  2. Make sure you have an internet connection (the extension downloads the language server on first use)
  3. Try reinstalling the extension

Syntax highlighting not working

Ensure your files have the .baml extension. The extension only activates for files with this extension.

Source Code

The Zed extension is developed as part of the BAML monorepo:

Feedback

If you encounter any issues or have feature requests, please: