mypy

Mypy doesn't like function attributes, https://github.com/python/mypy/issues/2087

This may seem like a good idea, but it gets problematic since you need to always use isinstance checks. Its actually discouraged to return union types by the mypy team: https://github.com/python/mypy/issues/1693

This looks interesting! I think the approach where a typed subset of Python is used to compile a fast extension module is the way forward for Python. This would leave us with a slow but dynamic high-level-variant (CPython) and typed lower-level-variant (EPython, mypyc & co) to compile performant extension modules, which you can easily import into your CPython code. The most prominent of such projects I know of is mypyc [0], which is already used to improve performance for mypy itself and the black [1] code formatter. I think it would be interesting to see how EPython compares to mypyc. [0] https://github.com/python/mypy/tree/master/mypyc [1] https://github.com/psf/black/pull/1009

The list should probably also include mypyc: https://github.com/python/mypy/tree/master/mypyc

You're basically talking about mypyc: https://github.com/python/mypy/tree/master/mypyc

black (the python auto formatter) uses mypyc https://github.com/python/mypy/tree/master/mypyc

> This is also very easy to achieve in Python by using Cython to selectively optimize code There is also mypyc [0] coming up on the horizon. https://github.com/python/mypy/tree/master/mypyc

From the FAQ[1]: > Does Coconut support static type checking? > Yes! Coconut compiles the newest, fanciest type annotation syntax into version-independent type comments which can then by checked using Coconut’s built-in MyPy Integration. So it uses MyPy. I've never seen documentation on what overall algorithm they use, and the code[2] is not an easy read. [1]: https://coconut.readthedocs.io/en/master/FAQ.html#does-cocon... [2]: https://github.com/python/mypy/blob/master/mypy/typeanal.py

Have you look at mypyc? https://github.com/python/mypy Its a compiler that support subset of python and mypy's team including Guido work on it. It would be great if this kind of efforts have been done on more realistic project.

And at mypyc https://github.com/python/mypy/tree/master/mypyc

you don't have to https://github.com/python/mypy/pull/5677

You can gradually annotate these packages locally for your project with [1], and then contribute it to [2]. Automatic stub generation may also be helpful [3] [1] https://github.com/python/mypy/wiki/Creating-Stubs-For-Pytho... [2] https://github.com/python/typeshed [3] https://mypy.readthedocs.io/en/stable/stubgen.html

Agreed on pattern matching, though mypy can help a lot here with exhaustive checks at the very least. They do work on enums and discriminated unions. They should document it: https://github.com/python/mypy/issues/6366 https://github.com/python/mypy/issues/5818

eventually there may be... https://github.com/python/mypy/tree/master/mypyc

Good call on the ingore_missing_imports. I just moved that from the [mypy] section into a [mypy-pyspark.*] and found 4 errors that I didn't notice before. The first result in Google for this error points here https://github.com/python/mypy/issues/3905 which explains the issue. I'm ashamed to say I probably just read the first reply, added it to my config and carried on with my day without actually reading what it did.