Static type checking à la mypy

[saada]

Would be amazing if Ruff had static type checking. Mypy is a well known solution in this area as well as pytype, pyre, and others.

As a follow up, we could have some way of auto-fixing type annotations.

Thank you for this incredible project 😍

[charliermarsh]

I will admit that I'm interested in this and it fits into the vision of what we're trying to do, but it would be irresponsible of me to promise or commit to anything yet :)

[NeilGirdhar]

I'm not sure if you are aware, but Pylyzer is a Python type checker that's written in Rust. It might be worth seeing if there's a way to have all the desired features with less effort.

[zanieb]

Oh that's interesting! It uses Erg and isn't quite feature complete, I'm not sure if we could use it but it's great to see another Rust Python tool.

[NeilGirdhar]

I don't know much about Rust, but would it be possible for them to expose an API that Ruff could call into? If so, the Ruff and Pylyzer teams could work out an API that Pylyzer exposes and Rust could call into? Even if you don't end up using Pylyzer, knowing the API that Ruff needs would be useful if Ruff were to implement its own type analysis. (Just thinking out loud.)

[thibaut-st]

Is there any dev started on that feature? It would be so awesome to have all the essential python code quality tools in one fast as hell dependency!

[nolanking90]

I'm interested in moving forward on this. I would like to begin working on features that could be exposed to ruff-lsp to add more of the traditional LSP capabilities, and it sounds like getting some type checking/inference working is going to be necessary before something like 'textDocument/hover' can be handled (by ruff-lsp) in a useful way.

Some input from the maintainers about implementation would be helpful, if this is still something the core team is interested in.

[zanieb]

Thanks for expressing your interest! Unfortunately the scope of this feature is far too large for external contribution, it will require major architectural changes to Ruff and extensive collaboration with our team. We're moving in this direction though. We can mark any related issues that would be good for external contribution with a "help wanted" label, as I'm sure there will be lots of smaller tasks that arise.

We're also recently kicked off a rewrite of ruff-lsp in Rust, see #10158. Once it's established, I'm sure there will be issues in that project that are good for contribution.