def test_writer_monad_law_associativity(self):
# (m >>= f) >>= g is just like doing m >>= (\x -> f x >>= g)
add1000 = "Added 1000 to %s"
mul100 = "Multiplied %s by 100"
a = Writer.unit(42).bind(
lambda x: Writer(x+1000, add1000 % x)).bind(
lambda y: Writer(y*100, mul100 % y))
b = Writer.unit(42).bind(
lambda x: Writer(x+1000, add1000 % x).bind(
lambda y: Writer(y*100, mul100 % y)
))
self.assertEqual(a, b)
def test_writer_monad_law_associativity(self):
# (m >>= f) >>= g is just like doing m >>= (\x -> f x >>= g)
add1000 = "Added 1000 to %s"
mul100 = "Multiplied %s by 100"
a = Writer.unit(42).bind(lambda x: Writer(x + 1000, add1000 % x)).bind(
lambda y: Writer(y * 100, mul100 % y))
b = Writer.unit(42).bind(lambda x: Writer(x + 1000, add1000 % x).bind(
lambda y: Writer(y * 100, mul100 % y)))
self.assertEqual(a, b)
def test_writer_return(self):
w = Writer.unit(42)
self.assertEqual(w.run(), (42, ""))
def test_writer_monad_law_right_identity(self):
# m >>= return is no different than just m.
a = Writer.unit(42).bind(Writer.unit)
self.assertEqual(a, Writer.unit(42))
def test_writer_monad_law_left_identity(self):
# return x >>= f == f x
entry = "Added 100000 to %s"
a = Writer.unit(42).bind(lambda x: Writer(x + 100000, entry % x))
b = (lambda x: Writer(x + 100000, entry % x))(42)
self.assertEqual(a, b)
def test_writer_monad_bind(self):
entry = "Multiplied by 10"
m = Writer.unit(42).bind(lambda x: Writer(x * 10, entry))
self.assertEqual(m, Writer(420, entry))
def test_writer_unitint_log(self):
IntWriter = Writer.create("IntWriter", int)
w = IntWriter.unit(42)
self.assertEqual(w.run(), (42, 0))
def test_writer_return(self):
w = Writer.unit(42)
self.assertEqual(w.run(), (42, ""))
def test_writer_monad_law_right_identity(self):
# m >>= return is no different than just m.
a = Writer.unit(42).bind(Writer.unit)
self.assertEqual(a, Writer.unit(42))
def test_writer_monad_law_left_identity(self):
# return x >>= f == f x
entry = "Added 100000 to %s"
a = Writer.unit(42).bind(lambda x: Writer(x+100000, entry % x))
b = (lambda x: Writer(x+100000, entry % x))(42)
self.assertEqual(a, b)
def test_writer_monad_bind(self):
entry = "Multiplied by 10"
m = Writer.unit(42).bind(lambda x: Writer(x*10, entry))
self.assertEqual(m, Writer(420, entry))
def test_writer_unitint_log(self):
IntWriter = Writer.factory("IntWriter", int)
w = IntWriter.unit(42)
self.assertEqual(w.run(), (42, 0))