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Type inference of list comprehension and Optional[t] #1734
Description
Activity
Rather than being strict optional specific, this is a general problem with Unions:
from typing import Optional, List, Union a = [] # type: List[Union[int, str]] b = [x for x in a if isinstance(x, int)] reveal_type(b) # E: Revealed type is 'builtins.list[Union[builtins.int, builtins.str]]'
- added a commit that references this issue
on Aug 9, 2016
The type of
bis incorrectlyList[Union[None, int]]instead ofList[int]when using--strict-optional:Generators and other comprehensions are related (not checked them).