mu

mu is a small language that transpiles to Python. A file is indented blocks without colons, calls of one argument without brackets, .. ranges, x -> ... lambdas, <- push, folds (sum for x in xs: f(x)), memo for a cached function with cases, and class for a Python class. The Python it produces is plain and runs anywhere; the transpiler pastes in the source of every helper the file calls.

pip install mu-language
mu file.mu        # the Python
mu --fmt file.mu  # the file, formatted
mu-repl           # a REPL

Spec

The language is specified one version at a time: v0.1, v0.2, v0.3, v0.4, v0.5, v0.6, v0.7, v0.8, v0.9, v0.10.

Profiles

The language owns a few helpers (Grid, deep). The rest come from a profile: a Python file that registers a project's library with mulang.library(module, *names) and the names its run time preloads with mulang.environment(objects). A project names its profile in pyproject.toml:

[tool.mu]
profile = "mu/leetmu.py"

python -m mulang, the REPL, py2mu and the ide load it from the working directory, or from the workspace root the ide is asked about. The first profile is the LeetCode one in the leet repo, whose library is the pydsa package (not yet published).

Tools

• mulang.ide: hover, completion, go-to-definition and signature help over JSON lines, through the transpiled Python and Jedi.
• mulang.py2mu: a Python solution written as mu, in as few lines as the language allows.
• vscode/: the VS Code extension (highlighting, formatter, the ide, a debugger that steps through the mu file). Link it into ~/.vscode/extensions and reload the window.

Tests

pip install -e '.[test]'
pytest

The tests also need pydsa, the leet profile's library, on the path. Two of them run only under the leet harness, whose sitecustomize preloads the names LeetCode preloads; elsewhere they skip.