mu for VS Code

Support for mu, a small language that transpiles to Python: highlighting, formatting on save, hover, completion, go-to-definition, signature help, and a debugger that steps through the mu file while debugpy runs the Python it produced.

Install

Download mu-<version>.vsix from the latest vscode-v* release. In VS Code:

code --install-extension mu-<version>.vsix

In VS Code, Cursor, VSCodium or Windsurf, the extensions view's menu also has "Install from VSIX".

Setup

The extension runs the mulang package in a Python of your choice. Install it there, with Jedi for the editor features:

pip install 'mu-language[ide]'

Then point the extension at that interpreter if it is not python3:

"mu.python": "${workspaceFolder}/.venv/bin/python"

Highlighting needs nothing installed. Formatting needs mu-language. Hover, completion, go-to-definition and signature help need Jedi, which the ide extra brings. Debugging needs the Python Debugger extension (ms-python.debugpy, installed as a dependency) and a debug script in the workspace; see below.

Settings

Setting	Default	Meaning
mu.python	python3	The interpreter that runs mulang.
mu.debugScript	mu/session.py	A script under the workspace root that debug [file.mu] writes the Python and its line map with, and prints the Python file's path.
mu.debugLogDir	unset	When set, debugpy's logs go to this folder.

.mu files format on save with two-space indentation; both are set in the extension's configuration defaults and can be overridden per workspace.

Debugging

Press F5 in a .mu file, or use the run button in the editor title. The extension calls the debug script, which transpiles the file and writes a line map, then starts debugpy on the Python with a proxy in between. Breakpoints set on mu lines land on the first Python line each produced, stack frames are reported at their mu line, and one step is one mu line.

A debug script is a small Python program that takes debug file.mu, writes file.py and a JSON line map next to it, and prints the path of the Python file. The one in the project this language came from is mu/session.py.

Development

cd vscode
ln -sfn "$PWD" ~/.vscode/extensions/shyal.mu-dev   # then reload the window
npm test                                            # the debug adapter
npx @vscode/vsce package                            # a .vsix

Releases are tagged vscode-v<version>; the vscode workflow in this repository attaches the .vsix to a GitHub release.