Python で Zコンビネータ

fix.py

fix = lambda f: (lambda g: g(g))(lambda g: f(lambda *args, **kwargs: g(g)(*args, **kwargs)))

fact = fix(lambda f: lambda n: 1 if n == 0 else n * f(n - 1))
fib = fix(lambda f: lambda x: 1 if x == 0 else 1 if x == 1 else f(x - 1) + f(x - 2))
gcd = fix(lambda f: lambda a, b: abs(a) if b == 0 else f(b, a % b))
tarai = fix(lambda f: lambda x, y, z: y if x <= y else f(f(x - 1, y, z), f(y - 1, z, x), f(z - 1, x, y)))