Description
Feature
Allow the use of the in statement when doing exhaustiveness checking.
from enum import Enum
from typing import assert_never
class MyEnum(Enum):
A = 1
B = 2
C = 3
def my_function(a: MyEnum) -> bool:
if a == MyEnum.A:
return True
elif a in (MyEnum.B, MyEnum.C):
return False
assert_never(a)
my_function(MyEnum.A)Currently, this will raise the following exception:
error: Argument 1 to "assert_never" has incompatible type
"Literal[MyEnum.B, MyEnum.C]"; expected "NoReturn" [arg-type]
assert_never(a)
where the following would not:
def my_function(a: MyEnum) -> bool:
if a == MyEnum.A:
return True
elif a == MyEnum.B:
return False
elif a == MyEnum.C:
return False
assert_never(a)Pitch
If you wish to do the same thing for multiple enums in that particular function and also want exhaustiveness checking, you need to type each case out individually and then return the same thing, which is not great (DRY etc...).