def test_monad_left_identity() -> None:
n: int = 3
def f(n: int) -> Reader[int, int]:
return Reader.pure(n * 3)
m: Reader[int, int] = Reader.pure(n)
assert m.bind(f)(0) == f(n)(0)
def test_monad_associativity() -> None:
m: Reader[int, int] = Reader.pure(3)
def f(n: int) -> Reader[int, int]:
return Reader.pure(n * 3)
def g(n: int) -> Reader[int, int]:
return Reader.pure(n + 5)
assert m.bind(f).bind(g)(0) == m.bind(lambda x: f(x).bind(g))(0)
def test_types() -> None:
m: Reader[Any, int] = Reader.pure(1)
map: Reader[Any, int] = m.map(lambda x: x)
map_operator: Reader[Any, int] = m * (lambda x: x)
bind: Reader[Any, int] = m.bind(lambda x: Reader.pure(x))
bind_operator: Reader[Any, int] = m >> (lambda x: Reader.pure(x))
apply: Reader[Any, int] = m.apply(Reader.pure(lambda x: x))
apply_operator: Reader[Any, int] = Reader.pure(lambda x: x) & m
sequence: Reader[Any, List[int]] = Reader.sequence([m])
def test_pure_annotation_includes_concrete_type() -> None:
assert int == inspect.signature(Reader.pure(5)).return_annotation
def g(n: int) -> Reader[int, int]:
return Reader.pure(n + 5)
def f(n: int) -> Reader[int, int]:
return Reader.pure(n * 3)
def test_monad_right_identity() -> None:
m: Reader[int, int] = Reader.pure(3)
assert m(0) == m.bind(lambda x: Reader.pure(x))(0)
def test_monad_bind_rshift_operator() -> None:
m: Reader[int, int] = Reader.pure(2)
f: Callable[[int], Reader[int, int]] = lambda x: Reader.pure(x + 1)
assert m.bind(f)(0) == (m >> f)(0)
def test_monad_bind() -> None:
expected: Reader[int, int] = Reader.pure(2)
m: Reader[int, int] = Reader.pure(1)
assert expected(0) == m.bind(lambda x: Reader.pure(x + 1))(0)
def test_applicative_fmap_using_ap() -> None:
f: Callable[[int], int] = lambda x: x + 1
m: Reader[int, int] = Reader.pure(3)
assert m.map(f)(0) == m.apply(Reader.pure(f))(0)
def test_functor_map_rmul_operator() -> None:
m: Reader = Reader.pure(3)
identity: Callable[[T], T] = lambda x: x
assert m.map(identity)(0) == (identity * m)(0)
def test_functor_associativity() -> None:
f: Callable[[int], int] = lambda x: x + 1
g: Callable[[int], str] = lambda x: str(x)
m: Reader[int, int] = Reader.pure(3)
assert m.map(lambda x: g(f(x)))(0) == m.map(f).map(g)(0)
def test_functor_identity() -> None:
m: Reader = Reader.pure(3)
identity: Callable[[T], T] = lambda x: x
assert m(0) == m.map(identity)(0)