Meta Just Dropped a NEW Python Type Checker!

Meta just released Pyrefly Beta, a new high-performance Python type checker and language server capable of analyzing up to 1.8 million lines per second, redefining what’s possible in Python. This video explains the Pyrefly Beta release, covering its fast type checking, advanced type inference, and deep support for Django, Pydantic, and modern Python typing. Built at Instagram scale and now open-source, Pyrefly is engineered to handle massive codebases while improving accuracy and developer workflow. ❤️ More about us Radically better observability stack: https://betterstack.com/ Written tutorials: https://betterstack.com/community/ Example projects: https://github.com/BetterStackHQ 📱 Socials Twitter: https://twitter.com/betterstackhq Instagram: https://www.instagram.com/betterstackhq/ TikTok: https://www.tiktok.com/@betterstack LinkedIn: https://www.linkedin.com/company/betterstack 📌 Chapters: 0:00 – Meta Drops a NEW Python Type Checker 0:33 – What Is Pyrefly? Meta’s Next-Gen Python Type Checker Explained 1:10 – Why Meta Built Pyrefly for Instagram-Scale Python Codebases 1:53 – Pyrefly Features Overview: Autocomplete, Type Inference, Navigation 2:36 – How Pyrefly Achieves 1.8 Million Lines Per Second (Performance Deep Dive) 3:46 – Advanced Type Checking: Django, Pydantic, NumPy Support 4:18 – Smart Import Resolution and Built-In Python Stubs Explained 4:28 – Migrating from Mypy or Pyright to Pyrefly 5:22 – Pyrefly Beta Status: Conformance, Bug Fixes, Weekly Updates 5:50 – Pyrefly Roadmap Toward v1.0 and Future Python Ecosystem Impact 6:20 – Should You Switch to Pyrefly? Honest Thoughts