def test_Maybe_wrap():
@Maybe.as_wrapper(checker=lambda x: x % 2)
def derp(x):
'Subtract one from a number.'
return x - 1
assert derp.__name__ == 'derp'
assert derp.__doc__ == 'Subtract one from a number.'
assert derp(2) == Just(1)
assert derp(3) == Nothing
assert derp(12).fmap(lambda x: x//2).or_else(1) == Just(5)
def test_Nothing_propagates():
assert (Just(2) >> n_add_two >> add_two) is Nothing
def test_Just_chain_many():
x = Just(2).fmap(add_two).bind(m_add_two).filter(lambda x: not x % 3) \
.or_else(Just(3))
assert x == Just(6)
def test_Nothing_or_call():
assert Nothing.or_call(add_two, 2) == Just(4)
def test_mapM():
assert lifted.mapM(m_add_two, *range(5)) == Just(List(2, 3, 4, 5, 6))
def test_mcons():
assert lifted.mcons(Just(0), Just(List(1, 2, 3))) == Just(List(0, 1, 2, 3))
assert lifted.mcons(Nothing, Just(List(0))) is Nothing
def test_lift_func():
assert lifted.lift(add_two, 2, Just) == Just(4)
def test_unit_func():
assert lifted.unit(2, Just) == Just(2)
def test_Just_bind():
assert (Just(2) >> m_add_two) == Just(4)
def test_just_apply():
assert Just(add_two).apply(Just(2)) == Just(4)
def test_just_fmap():
assert Just(2).fmap(add_two) == Just(4)
def test_Maybe_to_Either():
assert Just(4).to_either(None) == Right(4)
assert Nothing.to_either('failure') == Left('failure')
def test_truthiness():
assert not bool(Nothing)
assert bool(Just(1))
assert Nothing == Nothing
assert Just(1) == Just(1)
def test_maybe_custom_check():
c = lambda x: x & 1
assert Maybe(1, checker=c) == Just(1)
assert Maybe(2, checker=c) is Nothing
def test_identity():
assert pure.identity(2) == 2
assert Just(2).fmap(pure.identity) == Just(2)
def test_Just_get_or():
assert Just(2).get_or(3) == 2
from pynads import Just, List, Nothing
from pynads.funcs import lifted
add_two = lambda x: x + 2
curried_add = lambda x: lambda y: x + y
m_add_two = lambda x: Just(x + 2)
def test_fmap_func():
assert lifted.fmap(add_two, Just(2)) == Just(4)
def test_unit_func():
assert lifted.unit(2, Just) == Just(2)
def test_multiapply():
j = Just.unit(curried_add)
js = [Just(2), Just(2)]
assert lifted.multiapply(j, *js) == Just(4)
def test_lift_func():
assert lifted.lift(add_two, 2, Just) == Just(4)
def test_multibind():
j = Just.unit(2)
assert lifted.multibind(j, m_add_two, m_add_two) == Just(6)
def test_Just_get_or_call():
assert Just(2).get_or_call(add_two, 1) == 2
def test_multiapply():
j = Just.unit(curried_add)
js = [Just(2), Just(2)]
assert lifted.multiapply(j, *js) == Just(4)
def test_Just_or_else():
assert Just(2).or_else(Nothing) == Just(2)
def test_multibind():
j = Just.unit(2)
assert lifted.multibind(j, m_add_two, m_add_two) == Just(6)
def test_Just_or_call():
assert Just(2).or_call(m_add_two, 1) == Just(2)
def test_sequence():
justs = [Just(x) for x in range(5)]
assert lifted.sequence(*justs) == Just(List(0, 1, 2, 3, 4))
assert lifted.sequence(Nothing, *justs) is Nothing
def test_Just_filter():
assert Just(2).filter(lambda x: x % 2 == 0) == Just(2)
def test_fmap_func():
assert lifted.fmap(add_two, Just(2)) == Just(4)
def test_Nothing_or_else():
assert Nothing.or_else(4) == Just(4)