continuations.py

from itertools import *

class Cont(object):
    def __init__(self, func, *args):
        self.args = args
        self.func = func
        self.done = False
    
    def next(self):
        if self.done:
            raise StopIteration

        result = self.func(*self.args)
        if isinstance(result, Cont):
            self.func = result.func
            self.args = result.args
            return result
        else:
            self.done = True
            return result
    def __iter__(self):
        return self


def gcd(x,y, msg):
    print msg
    if y == 0:
        return x
    return Cont(gcd, y, x % y, msg)

def factorial(acc, n):
    if n == 0:
        return acc
    else:
        return Cont(factorial, acc*n, n-1)


foo = gcd(1345, 2332434, "lol")
bar = gcd(1345, 2223150, "hey")
print list(((x,y) for x,y in izip(foo, bar)))


foo = gcd(1345, 2332434, "lol")
bar = gcd(1345, 2223150, "hey")

print list(x for x in bar for y in foo)


bar = gcd(1345, 2223150, "hey")
foo = gcd(1345, 2332434, "lol")

print list(islice(foo, 0, 3))

print list(factorial(1,5))