y-combinator python

ycomb.py

from __future__ import print_function

#Y-combinator
Y = lambda f: (lambda x: x(x))(lambda x: f(lambda *args: x(x)(*args)))

#fact
print(Y(lambda f: lambda n: 1 if n == 1 else n * f(n - 1))(5))  #120

#sum
print(Y(lambda f: lambda n: 1 if n == 1 else n + f(n - 1))(100))  #5050

#fib
print(Y(lambda f: lambda n: n if n == 1 or n == 0 else f(n - 1) + f(n - 2))(10)) #55

#without using 'Y'
print((lambda f:
        (lambda x: x(x))
        (lambda x: f(lambda *args: x(x)(*args))))
        (lambda f: lambda n: 1 if n == 1 else n * f(n - 1))(5))  #120