cps/trampoline

 1 #!/usr/bin/env python
 2 # -*- coding: utf-8 -*-
 3 
 4 # the cps version
 5 def s(n, f):
 6     if n < 1:
 7         return f(n)
 8     return s(n-1,
 9              lambda x: f(x + n))
10 
11 # the trampoline version
12 def t_s(n, f):
13     if n < 1:
14         return lambda :f(n)
15     return lambda : t_s(n-1, lambda x: f(x + n))
16 
17 def trampoline(f):
18     while hasattr(f, ‘__call__‘):
19         f = f()
20     return f
21 
22 if __name__ == ‘__main__‘:
23     print s(10, lambda x: x)
24     print trampoline(t_s(10, lambda x: x))