import nat
import prelude

fib : Integer -> Integer
fib 0 = 1
fib 1 = 1
fib n = fib (n-1) + fib (n-2)

fibNat : Nat -> Nat
fibNat Zero = Succ Zero
fibNat (Succ Zero) = Succ Zero
fibNat (Succ (Succ n)) = plus Nat add_Nat (fibNat (Succ n)) (fibNat n)