Pyrefly is a next-generation Python type checker and language server, designed to be extremely fast and featuring advanced refactoring and type inference capabilities. This isn’t the Pyrefly team’s first time building a type checker for Python: Pyrefly is a successor to Pyre, the previous type checker our team developed. A lot of Pyrefly’s design comes directly from our experience with Pyre. Some things worked well at scale, while other things were harder to live with day-to-day.
