> Hm, I think it would be fine if there *was* no distinction. IOW if
>
> def foo(a: None) -> None: pass
>
> was indistinguishable from
>
> def foo(a): pass
>
> In fact I think I'd prefer it that way. Having an explicit way to say
> "no type here, move along" sounds fine.
I'd like to urge against making None magical -- I don't see any reason for
it.
Instead, consider that if I say
def foo(a: T1) -> T2:
I am presumably going to accept an argument of type T1 or a type derived
from T1, and return a result of type T2 or a type derived from T2. In which
case,
def foo(a): pass
should be equivalent to
def foo(a: object) -> object: pass
and we don't need to recycle None for the purpose -- especially as
ininstance(None,object) yields True and I presume that isn't going to
change.
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