cps/trampoline version

cps

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# the cps version
def s(n, f):
    if n < 1:
        return f(n)
    return s(n-1,
             lambda x: f(x + n))

# the trampoline version
def t_s(n, f):
    if n < 1:
        return lambda :f(n)
    return lambda : t_s(n-1, lambda x: f(x + n))

def trampoline(f):
    while hasattr(f, '__call__'):
        f = f()
    return f

if __name__ == '__main__':
    print s(10, lambda x: x)
    print trampoline(t_s(10, lambda x: x))