We’re building a new static type checker for Python, from scratch, in Rust. From a technical perspective, it’s probably our most ambitious project yet. We’re about 800 PRs deep!
Like Ruff and uv, there will be a significant focus on performance. The entire system is designed to be highly incremental so that it can eventually power a language server (e.g., only re-analyze affected files on code change). [...]
We haven't publicized it to-date, but all of this work has been happening in the open, in the Ruff repository.
Recent articles
- First impressions of Claude Cowork, Anthropic's general agent - 12th January 2026
- My answers to the questions I posed about porting open source code with LLMs - 11th January 2026
- Fly's new Sprites.dev addresses both developer sandboxes and API sandboxes at the same time - 9th January 2026