Tuple[...] should be compatible with Iterable[...] and Sequence[...]

[JukkaL]

Currently, Tuple[int, int] is not compatible with Iterable[int] and Sequence[int], but it should obviously be. Also, update type join to support this (join of Tuple[int, int] and Tuple[int] should be Sequence[int]).

For example, this program is rejected:

from typing import Iterable
def f(x: Iterable[int]) -> None: pass
f([1,2])  # OK
f((1,2))  # Argument 1 to "f" has incompatible type "Tuple[int, int]"

See also #184 (it's very closely related).

[JukkaL]

Implementation waiting to be merged in the type-system-features branch: afe4c57

[terrisgit]

This problem still exists in 2018... mypy==.580

async def execute_update(query: str, query_args: Sequence[Any]=None)->None:
pass

await DbExecutor.execute_update("select 1", (5))

error: Argument 2 to "execute_update" has incompatible type "int"; expected "Optional[Sequence[Any]]"

Resolution is to use [5] instead of (5) ... which is not what I want

Why is this closed?

[Michael0x2a]

@terrisgit -- (5) isn't actually a tuple -- that expression is equal to just 5.

If you instead pass in (5,), everything typechecks.

[gvanrossum]

Gotta give points for the attitude.

[terrisgit]

Thanks for the education!

[user-name-name]

I have a next case: the result of one function is Dict[str, Tuple[str, ...]], the argument of another one is Dict[str, Sequence[str]]. So when we use use the result of the first function as the argument of the second, we got "Argument has incompatible type Dict[str, Tuple[str, ...]]"; expected "Dict[str, Sequence[str]]". Is it valid?

[ilevkivskyi]

@user-name-name Mypy is correct, Dict is invariant https://mypy.readthedocs.io/en/latest/generics.html#variance-of-generic-types