Source code for returns.pointfree.bind_io

from __future__ import annotations

from typing import TYPE_CHECKING, Callable, TypeVar

from import IOLikeN
from import Kinded, KindN, kinded

    from import IO  # noqa: WPS433

_FirstType = TypeVar('_FirstType', contravariant=True)
_SecondType = TypeVar('_SecondType')
_ThirdType = TypeVar('_ThirdType', contravariant=True)
_UpdatedType = TypeVar('_UpdatedType', covariant=True)

_IOLikeKind = TypeVar('_IOLikeKind', bound=IOLikeN)

[docs]def bind_io( function: Callable[[_FirstType], IO[_UpdatedType]], ) -> Kinded[Callable[ [KindN[_IOLikeKind, _FirstType, _SecondType, _ThirdType]], KindN[_IOLikeKind, _UpdatedType, _SecondType, _ThirdType], ]]: """ Composes successful container with a function that returns a container. In other words, it modifies the function's signature from: ``a -> IO[b]`` to: ``Container[a, c] -> Container[b, c]`` .. code:: python >>> from import IOSuccess, IOFailure >>> from import IO >>> from returns.pointfree import bind_io >>> def returns_io(arg: int) -> IO[int]: ... return IO(arg + 1) >>> bound = bind_io(returns_io) >>> assert bound(IO(1)) == IO(2) >>> assert bound(IOSuccess(1)) == IOSuccess(2) >>> assert bound(IOFailure(1)) == IOFailure(1) """ @kinded def factory( container: KindN[_IOLikeKind, _FirstType, _SecondType, _ThirdType], ) -> KindN[_IOLikeKind, _UpdatedType, _SecondType, _ThirdType]: return container.bind_io(function) return factory