Pylance + Pyrefly: Python Type Checker Is Now Swappable

Microsoft broke Pylance’s exclusive relationship with Pyright last week. The Type Server Protocol (TSP) is a new open standard that lets Pylance accept any compliant type checker as its backend — and Pyrefly, Meta’s Rust-powered type checker, is the first to plug in. If you use VS Code for Python, this changes how type checking works in your editor. What the Type Server Protocol Changes Until now, Pylance and Pyright were inseparable. Pylance handled IDE features like completions, Quick Info, and Copilot integration; Pyright did the type analysis underneath. You got one without a say in the other. TSP draws […]

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