def test_traverse_some(self):
xs = toLinkedList([1, 2, 3])
def add1A(x):
return some(x + 1)
self.assertEqual(Option.traverse(add1A, xs),
some(toLinkedList([2, 3, 4])))
def test_functor_associativity_law(self):
a = some(1)
def f(x):
return x + 1
def g(x):
return x * 2
self.assertEqual(a.map(f).map(g), a.map(f | andThen | g))
def test_ap(self):
def add(x):
return lambda y: x + y
self.assertEqual(some(add).ap(some(1)).ap(some(2)), some(3))
self.assertEqual(some(add).ap(nothing).ap(some(2)), nothing)
def test_map(self):
def f(x):
return x + 1
self.assertEqual(some(1).map(f), some(2))
self.assertEqual(nothing.map(f), nothing)
def test_functor_identity_law(self):
a = some(1)
self.assertEqual(identity(a), a.map(identity))
self.assertEqual(identity(nothing), nothing.map(identity))
def test_isSome(self):
self.assertFalse(nothing.isSome())
self.assertTrue(some(1).isSome())
def oddA(x):
if x % 2 == 1:
return some(x)
else:
return nothing
def add1A(x):
return some(x + 1)
def test_sequence_nothing(self):
self.assertEqual(
Option.sequence(toLinkedList([some(1), nothing,
some(3)])), nothing)
def test_sequence_some(self):
xs = toLinkedList([some(1), some(2), some(3)])
self.assertEqual(Option.sequence(xs), some(toLinkedList([1, 2, 3])))
def test_fold(self):
def toStr(a, z):
return str(a) + ", " + z
self.assertEqual(some(1).fold(toStr, "0"), "1, 0")
self.assertEqual(nothing.fold(toStr, "0"), "0")
def test_eq_some(self):
self.assertEqual(some(1), some(1))
self.assertNotEqual(some(0), some(1))
def add1M(x):
return some(x + 1)
def test_bind(self):
def add1M(x):
return some(x + 1)
self.assertEqual(some(2).bind(add1M), some(3))
self.assertEqual(nothing.bind(add1M), nothing)