Please use int and float instead of numbers.Integral/Real

PEP 484 intentionally recommends using int/float instead of the numeric ABCs, and mypy doesn’t like them at all:

from numbers import Integral, Real
def f(i: Integral, x: Real) -> Real:
    return i * x
f(1, 3.14)

gives these errors:

__tmp__.py:4: error: Argument 1 to "f" has incompatible type "int"; expected "Integral"
__tmp__.py:4: error: Argument 2 to "f" has incompatible type "float"; expected "Real"

[posita]

If you really believe that Stone has important uses for numpy numbers in annotations then maybe we need to talk …

I’m not sure I have an example in mind that isn’t solved by some kind of “casting” before use. (Even Python-Future’s int subclasses long.)

Personally I think PEP 3141 is a dead end. Very few people import the numbers module to use with isinstance() or issubclass() and even fewer use it to implement their own numeric types; and very few people writing numeric code care whether their code works for numbers that aren’t instances of the concrete classes they themselves use regularly.

Perhaps I am being (overly) nervous as a “purist”? Other than PEP 484, I can’t find any official suggestion that PEP 3141 should be avoided or treated as deprecated. True, its use is probably rare, or an afterthought, but it just feels dirty that type checking should ever be incompatible with ABCs. But maybe I’ll just up my dose of Sertraline and move on. 😏

(Referencing python/mypy#2636 for background.)

[zero323]

Thanks @gvanrossum.