python.md

Python

Python is managed with uv — version installation, virtual environments, and dependencies. uv itself comes from mise.

mise is configured with python.uv_venv_auto = "source", so a .venv in the current directory is activated automatically on cd — there is usually no need to activate by hand.

Installing Python versions

uv python install 3.13        # install latest 3.13
uv python install 3.12.4      # install a specific version
uv python list                # list installed and available versions

Virtual environments

mkvenv creates a virtual environment in the current directory:

mkvenv          # create .venv using the latest installed Python
mkvenv 3.12     # create .venv using Python 3.12

mise picks it up on entry. If you want to activate one manually:

source .venv/bin/activate.fish

Projects

For projects with a pyproject.toml, uv manages dependencies directly:

uv init                    # create a new project
uv add requests            # add a dependency
uv sync                    # install all dependencies
uv run python script.py    # run inside the project environment

Upgrading dependencies

uvu    # uv lock --upgrade && uv sync

This upgrades everything allowed by pyproject.toml and syncs the environment.

Listing outdated packages

plo    # uv pip list --outdated (falls back to pip)

mise vs uv

mise can also manage Python versions, and it is what provides the python on PATH. uv is preferred for per-project work, since it owns the lockfile and the venv.

Shell completions

Generated in config.fish:

uv generate-shell-completion fish | source