2 > data Boolean = FF | TT
3 > data Pair a b = MkPair a b
4 > data LList alpha = Nill | Conss alpha (LList alpha)
5 > data Nat = Zero | Succ Nat
6 > data Tree x = Leaf x | Node (Tree x) (Tree x)
7 > data A a = MkA a (A a)
9 > append :: LList a -> LList a -> LList a
10 > append xs ys = case xs of
11 > Conss z zs -> Conss z (append zs ys)