#test.py#

 
def solution(xs):
    # write your code in Python 3.6
    
    x, xs = uncons(range(0,20))

    print(x)
    print(xs)

# f should be capable of handling all Cardinalities of input, xs
# so ideally its a heterogeneus list 
def fmap(f, xs): 
    if len(xs) == 0: # case xs of [] 
        return xs
    else:
        x2,xs2 = uncons(xs)
        x2 = f(x2)
        g = [x2] + [2]
        return  [x2] + fmap(f, xs2)
    

#someFunc will either be comparing a <-> b or a <-> bs

# f :: mempty -> x -> mempty
def foldr(f, mempty, xs):
    x = f(mempty, xs.pop(0))
    if len(xs) != 0:  
        out = foldr (f, x, xs)
        return out 
    else:
        return x

    
def foldrLookAhead(f, mempty, xs):
    x = f(mempty, xs)
    
    
def uncons(xs): 
    if len(xs) != 0:
        x = xs.pop(0)
    return x, xs

def plusOne(x):
    return x + 1


def plus(x,y):
    return x + y
#print(fmap (plusOne, [i for i in range(0,9)]))


print(foldr(plus, 0, [i for i in range(0,9)]))