https://xcancel.com/charliermarsh/status/1884651482009477368
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).
Performance is just one of many goals, though.
For example: we’re investing heavily in strong theoretical foundations and a consistent model of Python’s typing semantics.
(We’re lucky to have @carljm and @AlexWaygood on the team for many reasons, this is one of them.)
Another goal: minimizing false positives, especially on untyped code, to make it easier for projects to adopt a type checker and expand coverage gradually over time, without being swamped in bogus type errors from the start.
We haven’t publicized it to-date, but all of this work has been happening in the open, in the Ruff repository.
All driven by a uniquely great team: @carljm, @AlexWaygood, @sharkdp86, @MichaReiser, @DhruvManilawala, @ibraheemdev, @dcreager.
I’m learning so much from them.
Warning: this project is not ready for real-world user testing, and certainly not for production use (yet). The core architecture is there, but we’re still lacking support for some critical features.
Right now, I’d only recommend trying it out if you’re looking to contribute.
For now, we’re working towards an initial alpha release. When it’s ready, I’ll make sure you know :)
In my experience, it’s a manageable trade off.
You allow for Python “magic” at the cost of type safety. Or you forgo magic for types, and the resiliency that comes with it.
Day to day, you don’t need magic. With good application of hinting you can stop many bugs before they appear.
When you do need magic, you can usually construct it to work within the type system, or at the very least easily ringfence the tainted typeless code the magic introduced.
The sync/async contradiction is much worse to wrangle.