Type hinting generator in Python 3.6

Question

According to PEP-484, we should be able to type hinting a generator function as follows:

from typing import Generator

def generate() -> Generator[int, None, None]:
    for i in range(10):
        yield i

for i in generate():
    print(i)

However, the list comprehension gives the following error in PyCharm.

Expected 'collections.Iterable', got 'Generator[int, None, None]' instead less... (⌘F1)

Any idea why PyCharm is considering this as error?

---

A few clarification after reading some answers. I am using PyCharm Community Edition 2016.3.2 (the latest version) and have imported the typing.Generator (updated in the code). The above code runs just fine, but PyCharm considers this an error:

So, I'm wondering if this is actually an error or an unsupported feature in PyCharm.

Solution

This isn't a direct answer to the question, but I think it is a better solution.

I'm using the typing specification below, using Iterator[int] instead of Generator. The validation is OK. I think it is a lot clearer. It better describes the code intention and is recommended by Python docs.

from typing import Iterator

def generate() -> Iterator[int]:
    for i in range(10):
        yield i

It would also allow future refactorings if you change your Generator for a list or other iterable.

I'm using Visual Studio Code with PyLance for typing validation. PyCharm mypy should have the same behavior.

Comments

[defance]

I am not sure why this got downvoted. The python doc itself states, that is it possible to use Iterator[YieldType] or Iterable[YieldType] for generators, which yield only. See docs.python.org/3.6/library/typing.html#typing.Generator

[thiagola92]

from collections.abc import Iterator is the new preferable way. See docs.python.org/3.10/library/typing.html#typing.Iterable