Python mypy — Static Type Checking

Mypy is an optional static type checker for Python that catches type errors at development time without runtime overhead. It combines the expressive power of Python with a powerful type system based on PEP 484, enabling gradual migration from dynamic to static typing.

Installation

pip install mypy

# Install type stubs for common third-party libraries
pip install types-requests types-PyYAML types-boto3

# Run mypy
mypy src/
mypy --strict src/

Core Annotation Patterns