while True:
yield element
def powerset(iterable):
"""Yields all possible subsets of the iterable
>>> list(powerset([1,2,3]))
[(), (1,), (2,), (3,), (1, 2), (1, 3), (2, 3), (1, 2, 3)]
"""
s = list(iterable)
return chain.from_iterable(combinations(s, r) for r in range(len(s) + 1))
# Return a tuple containing the next element in the sequence,
# and an iterable containing the rest of the sequence.
split = compose(lambda iterator, next=next: (next(iterator), iterator), iter)
def take(n, iterable, islice=islice):
"""
Take the first n elements of the given iterable.
"""
return islice(iterable, n)
def unique(iterable, filterfalse=filterfalse):
"""
Return only unique elements from the sequence.
"""
seen = set()
add = seen.add
def juxt(cls, func, *funcs):
return cls(compose(lift(func), juxt(*funcs)))
def constant(x):
"""Close x under an anonymous function."""
return lambda *args, **kwargs: x
@contextmanager
def context(func, *args, **kwargs):
"""Return a context for lazily evaluating a function with given input."""
yield func(*args, **kwargs)
# Return the number of position arguments in the given function.
nargs = compose(
partial(reduce, operator.sub),
partial(map, len),
compact,
operator.attrgetter('args', 'defaults'),
getargspec
)
def curry(func, n=None):
"""Curry a function for up to n arguments, where by default n is the number
of fixed, unnamed arguments in the function defintion.
"""
if n is None:
n = nargs(func)
# @wraps(func)
def curried(*args, **kwargs):
def compose(cls, *funcs):
return cls(compose(*funcs))
def test_compose(self):
c = common.compose(lambda x: x + 2, lambda y: y ** 2)
self.assertEqual(c(12), 146)
