More flexible type support for math.prod and math.sumprod

[cake-monotone]

Also related to #11913

Currently, math.prod and math.sumprod do not properly support Decimal, Fraction, complex, or possibly other numeric types. This makes it inconvenient to replace builtins.sum with math.prod in a straightforward manner.

from typing import reveal_type
from fractions import Fraction
from math import prod

a = prod([Fraction(1), Fraction(2)])
reveal_type(a)  # it should be Fraction | Literal[1], but float for now

prod([complex(1, 0), complex(1, 2)])

Mypy Playground Link

I believe it should be followed the type stub of builtins.sum, but I’m not sure what breaking changes this might cause.

[cake-monotone]

useful links

• type stub of builtins.sum
• type stub of math.prod
• type stub of math.sumprod

[srittau]

Any improvements here are welcome!

[cake-monotone]

Sounds good! I'll work on creating a PR for this issue.