New submission from Vaibhav Karve <[email protected]>:
If I run mypy on the following file called test.py, I get an error:
# test.py
from typing import Iterator, Tuple
import itertools as it
a : Iterator[Tuple[int, ...]]
a = it.product([1,2,3], repeat = 2)
b : Iterator[Tuple[int, ...]]
b = it.combinations([1,2,3], 2)
The line about a goes through without complain. But mypy complains about b by
printing the following error message--
test.py:8: error: Incompatible types in assignment (expression has type
"Iterable[Tuple[int, ...]]", variable has type "Iterator[Tuple[int, ...]]")
test.py:8: note: 'Iterable' is missing following 'Iterator' protocol member:
test.py:8: note: __next__
So basically, it.product is an Iterator but it.combinations is an Iterable (I
think it should be an iterator too). I think (without a lot of evidence) that
this is a bug in itertools and not in typing.
PS: I apologize if my comment is not formatted according to best practices.
This is my first time registering a new issue.
----------
components: Demos and Tools
messages: 327849
nosy: vaibhavkarve
priority: normal
severity: normal
status: open
title: itertools.combinations has wrong type when using the typing package
type: behavior
versions: Python 3.6
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Python tracker <[email protected]>
<https://bugs.python.org/issue35006>
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