fix = \f -> (\x -> & f (x x)) (\x -> & f (x x))

fac _ 0 = 1
fac f n = n * f (n - 1)

fib _ 0 = 0
fib _ 1 = 1
fib f n = f (n - 1) + f (n - 2)

(fix fac 12, fix fib 12)