type-checking language-server rust python-tooling performance

Astral releases ty, Rust-based Python type checker

ty performs incremental type checking 80–500x faster than Pyright/Pyrefly in editors by architecture-first design around LSP; replaces mypy/Pyright for projects prioritizing live-edit latency.

June 9, 2026

Summary

Live type diagnostics appear in 4.7ms instead of 386ms, eliminating editor lag during active development. Incremental re-computation means edits to central files in large projects (PyTorch-scale) stay interactive rather than blocking.

Why it matters

Implementation verdict

Ready for production in Beta. Install via `uv tool install ty@latest` or VS Code extension. Replaces mypy/Pyright if you value sub-10ms feedback loops; requires Python 3.8+. Stable release targeting 2025, but Astral already uses it exclusively. Worth adopting now if editor responsiveness is a bottleneck.

Sources

1.ty is an extremely fast Python type checker and language server, written in Rust, and designed as an alternative to tools like mypy, Pyright, and Pylance
2.after editing a load-bearing file in the PyTorch repository, ty recomputes diagnostics in 4.7ms: 80x faster than Pyright (386ms) and 500x faster than Pyrefly (2.38 seconds)
3.Without caching, ty is consistently between 10x and 60x faster than mypy and Pyright
4.We now use ty exclusively in our own projects and are ready to recommend it to motivated users for production use

Dev Signal

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