Pyrefly is a fast type checker for Python. It’s designed to replace the existing Pyre type checker at Meta by the end of 2025.
Pyrefly aims to increase development velocity with IDE features and by checking your Python code.
This is free and open source software.
Features include:
- Type Inference: Pyrefly infers types in most locations, apart from function parameters. It can infer types of variables and return types.
- Flow Types: Pyrefly can understand your program’s control flow to refine static types.
- Incrementality: Pyrefly aims for large-scale incrementality at the module level, with optimized checking and parallelism.
Website: github.com/facebook/pyrefly
Support:
Developer: Meta Platforms, Inc. and affiliates
License: MIT License
Pyrefly is written in Rust. Learn Rust with our recommended free books and free tutorials.
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