google/pytype

An update on pytype

TL;DR: The last supported Python version for Pytype will be 3.12. We are still very actively interested in the space of Python type checking, but shifting our investments towards new ideas and different frameworks.

Pytype's development began in 2012 to meet Google developers' demand for compile-time checking. Pytype started with using type inference and interface files, and then switched to inline annotations (while retaining the inference engine) after the acceptance of PEP 484. Later, pytype's team collaborated with Guido and mypy to create typeshed, a central repository for type annotations.

While pytype has been effective, its bytecode-based design has presented challenges in implementing new features (e.g. faster adoption of new typing PEPs) due to bytecode’s inherent instability and propensity to change. Consequently, we intend to focus our investments on exploring new typing approaches that are better suited for Google’s Python user base and make Python 3.12 the last supported version for pytype.

We encourage folks to investigate the mature and excellent alternative solutions for Python typing going forward. We would like to note that the Python typing ecosystem is very robust now, offering a wider array of mature solutions (see FAQ).

The creation and development of pytype was a collaborative effort, and we would like to thank all contributors to pytype, especially the four main contributors: Rebecca Chen, Martin DeMello, Teddy Sudol, and initial lead Matthias Kramm. We particularly recognize Rebecca Chen for her decade-long commitment to pytype and her significant contributions to Python's type system as a long-standing member of the typing council.