def associativity_law(
mappable: 'MappableN[_FirstType, _SecondType, _ThirdType]',
first: Callable[[_FirstType], _NewType1],
second: Callable[[_NewType1], _NewType2],
) -> None:
"""Mapping twice or mapping a composition is the same thing."""
assert_equal(
mappable.map(first).map(second),
mappable.map(compose(first, second)),
)
def associative_law(
altable: 'AltableN[_FirstType, _SecondType, _ThirdType]',
first: Callable[[_SecondType], _NewType1],
second: Callable[[_NewType1], _NewType2],
) -> None:
"""Mapping twice or mapping a composition is the same thing."""
assert_equal(
altable.alt(first).alt(second),
altable.alt(compose(first, second)),
)
def composition_law(
container: 'ApplicativeN[_FirstType, _SecondType, _ThirdType]',
first: Callable[[_FirstType], _NewType1],
second: Callable[[_NewType1], _NewType2],
) -> None:
"""
Composition law.
Apply two functions twice is the same
as applying their composition once.
"""
assert_equal(
container.apply(container.from_value(compose(first, second))),
container.apply(container.from_value(first), ).apply(
container.from_value(second), ),
)
def test_function_composition():
"""Ensures that functions can be composed and return type is correct."""
second_after_first = compose(_first, _second)
assert second_after_first(1) is True
assert second_after_first(0) is True