[Mehdi2277]

Typescript similarity is expected as maintainer of pyright does talk with typescript maintainers and sometimes pyright adds features inspired by typescript's inference.

I think the major reasons for mypy is if you are working on a library to be shared with many others (especially open source one) you'd like library to be compatible with mypy as your users are likely to use mypy as it's still most popular type checker. So for open source libraries it makes sense to use both mypy/pyright. For projects that you do not expect main users (company internal one you define standards) it's more fine to pick type checker you prefer. The other main place mypy can be helpful is plugins if you need some behavior outside of type system for a library you work with a lot.

Also pyright is implemented in typescript which does mean you'll need to have a CI dependency on javascript environment that python project's often don't need. Lastly for typical python developer it's a bit easier to make pull request to mypy vs pyright just as they normally have more python knowledge then javascript knowledge. This is pretty minor given most people don't debug there own type checker and pyright's bug list is very short.