def test_nothing_monad_law_associativity(self):
# (m >>= f) >>= g is just like doing m >>= (\x -> f x >>= g)
m = Nothing()
f = lambda x: unit(x + 1000)
g = lambda y: unit(y * 42)
self.assertEqual(m.bind(f).bind(g), m.bind(lambda x: f(x).bind(g)))
def test_nothing_applicative_law_homomorphism(self):
# pure f <*> pure x = pure (f x)
f = lambda x: x * 42
self.assertEqual(
pure(f).apply(Nothing()),
Nothing()
)
def test_nothing_functor_map(self):
f = lambda x: x+2
x = Nothing()
self.assertEquals(
x.map(f),
x
)
def test_nothing_monad_bind(self):
m = Nothing()
f = lambda x: unit(x*10)
self.assertEqual(
m.bind(f),
Nothing()
)
def test_nothing_monad_bind(self):
m = Nothing()
f = lambda x: unit(x*10)
self.assertEqual(
m.bind(f),
Nothing()
)
def test_nothing_functor_map(self):
f = lambda x: x + 2
x = Nothing()
self.assertEqual(
x.map(f),
x
)
def test_nothing_monad_law_left_identity(self):
# return x >>= f is the same thing as f x
f = lambda x: unit(x+100000)
self.assertEqual(
Nothing().bind(f),
Nothing()
)
def test_nothing_applicative_law_functor(self):
# pure f <*> x = fmap f x
x = Nothing()
f = lambda x: x * 42
self.assertEquals(
pure(f).apply(x),
x.map(f)
)
def test_nothing_monad_law_right_identity(self):
# m >>= return is no different than just m.
m = Nothing()
self.assertEqual(
m.bind(unit),
m
)
def test_nothing_applicative_law_interchange(self):
# u <*> pure y = pure ($ y) <*> u
u = unit(lambda x: x*42)
self.assertEqual(
u.apply(Nothing()),
Nothing().apply(u)
)
def test_nothing_applicative_law_functor(self):
# pure f <*> x = fmap f x
x = Nothing()
f = lambda x: x * 42
self.assertEqual(
pure(f).apply(x),
x.map(f)
)
def test_nothing_monad_law_right_identity(self):
# m >>= return is no different than just m.
m = Nothing()
self.assertEqual(
m.bind(unit),
m
)
def test_nothing_monad_law_associativity(self):
# (m >>= f) >>= g is just like doing m >>= (\x -> f x >>= g)
m = Nothing()
f = lambda x: unit(x+1000)
g = lambda y: unit(y*42)
self.assertEqual(
m.bind(f).bind(g),
m.bind(lambda x: f(x).bind(g))
)
def test_nothing_functor_law2(self):
# fmap (f . g) x = fmap f (fmap g x)
def f(x):
return x + 10
def g(x):
return x * 10
x = Nothing()
self.assertEquals(x.map(compose(f, g)), x.map(g).map(f))
def test_nothing_functor_law2(self):
# fmap (f . g) x = fmap f (fmap g x)
def f(x):
return x+10
def g(x):
return x*10
x = Nothing()
self.assertEquals(
x.map(compose(f, g)),
x.map(g).map(f)
)
def test_maybe_monoid_just_append_nothing(self):
m = Just("Python")
self.assertEqual(
m + Nothing(),
m
)
def test_nothing_applicative_law_identity(self):
# pure id <*> v = v
v = Nothing()
self.assertEqual(
pure(identity).apply(v),
v
)
def test_identity_applicative_law_composition(self):
# pure (.) <*> u <*> v <*> w = u <*> (v <*> w)
w = Nothing()
u = pure(lambda x: x * 42)
v = pure(lambda x: x + 42)
self.assertEquals(
pure(fmap).apply(u).apply(v).apply(w), u.apply(v.apply(w)))
def _get(self, _p, _fp, _d, default):
if len(_p) == 1:
try:
if isinstance(_d, dict) is True:
return Just(_d[_p[0]])
if isinstance(_d, DP) is True:
return Just(_d.raw()[_p[0]])
else:
return Nothing()
except KeyError:
if isinstance(default, Monad) is True:
return default
else:
return Just(default)
d = _d.get(_p[0], None)
if _d.get(_p[0], None) is None:
_fp.append(_p[0])
d = self._mkdir(_d, _p[0], _fp)
return self._get(_p[1:], _fp, d, default)
def dpget(ns, path):
res = ns.V(path)
if res == Nothing():
raise KeyError(path)
return res
def test_just_applicative_1(self):
a = Just.pure(lambda x, y: x + y).apply(Just(2)).apply(Just(40))
self.assertNotEquals(a, Nothing())
self.assertEquals(a, Just(42))
def test_maybe_monoid_nothing_append_just(self):
m = Just("Python")
self.assertEquals(Nothing().append(m), m)
def test_nothing_functor_law1(self):
# fmap id = id
self.assertEqual(
Nothing().map(identity),
Nothing()
)
def test_just_applicative_3(self):
a = Just.pure(lambda x, y: x+y).apply(Just(42)).apply(Nothing())
self.assertEqual(a, Nothing())
from oslash.maybe import Just, Nothing
Value = Just
NONE = Nothing()
TRUE = Just(True)
FALSE = Just(False)
def isNothing(x):
return x is None or x == NONE or isinstance(x, Nothing)
def get(self, path, default=Nothing()):
_p = os.path.abspath(path).split("/")
_p = [i for i in _p if i]
return self._get(_p, [""], self._value, default)
