#
# From the great idea of https://stackoverflow.com/a/24831722/7092558
# with some changes and tweaks.
#
# Example:
#  myList = range(20)
#  ret = compose(
#    myList,
#    filterBy(lambda n: n%2==0),
#    mapBy(lambda n: "even "+str(n)),
#    reduceBy(lambda sa, sb: sa+"\n"+sb)
#  )
#  assert(ret == 'even 0\neven 2\neven 4\neven 6\neven 8\neven 10\neven 12\neven 14\neven 16\neven 18')
#

import functools

def compose(arg, *functions):
    return generalCompose(*functions)(arg)

def generalCompose(*functions):
    return functools.reduce(lambda f, g: lambda x: f(g(x)), reversed(functions))

def mapBy(map_fn): return functools.partial(map, map_fn)

def filterBy(filter_fn): return functools.partial(filter, filter_fn)

def reduceBy(reduce_fn): return functools.partial(functools.reduce, reduce_fn)

def const(a): return lambda x: a

def find(predicate):
    def _find(iterable):
        for l in iterable:
            if predicate(l):
                return l
        return None
    return _find


def _alpt_testCompose():
  myList = range(20)
  ret = compose(
    myList,
    filterBy(lambda n: n%2==0),
    mapBy(lambda n: "even "+str(n)),
    reduceBy(lambda sa, sb: sa+"\n"+sb)
  )
  assert(ret == 'even 0\neven 2\neven 4\neven 6\neven 8\neven 10\neven 12\neven 14\neven 16\neven 18')

def _alpt_testFind():
    a = range(20)
    assert compose(a, filterBy(lambda n: n%2), find(lambda n: n == 7)) == 7

###

_alpt_testCompose()
_alpt_testFind()