Mypy Nova Extension

It’s a stand-alone Nova extension to use Mypy, an optional static type checker for Python.

Requirements

Before using the extension, it’s necessary to install Mypy itself if you don’t have one already.

Mypy can be installed simply by running pip install mypy.

Note: The --show-error-end option only exists in version 0.981 or higher. Remove it from the global extension configuration if using an earlier version. Yet it’s better to use the latest mypy available.

Configuration

The extension supports both global and workspace configurations. A workspace configuration always overrides a global one.

Options

There are three options available to configure: executable path, command arguments, and check mode. By default, the executable path is /usr/local/bin/mypy, with no additional arguments, and checking on changing.

You could alter the executable path if Mypy installed in a different place or if /usr/bin/env usage is desirable.

In the case of /usr/bin/env, it becomes the executable path, and mypy becomes the first argument.

Also, there is a Python executable path available as a workspace-only option. It’s just a handy alias for the --python-executable command argument.

mypy.ini

The extension respects pyproject.toml, mypy.ini, and .mypy.ini in a project directory as much as mypy command-line utility. So, there’s no need to specify the --config-file argument explicitly.

Caveats

Read-Write Entitlement

It requires the filesystem: read-write entitlement because of the Mypy inability to read from stdin, so the extension utilizes temporary shadow-files to solve it in case of check on change mode.