module Product;

// Already defined!
// let rec foldr f b xs = match xs with
//   | [] -> b
//   | (x::xs) -> f x (foldr f b xs)
// ;;

// let product ms ns = foldr (fun m ps -> foldr (fun n xs -> (m,n)::xs) ps ns) [] ms;;

def List<Pair<A,B>> productP<A,B>(List<A> ms, List<B> ns) =
    foldr((A m, List<A> ps) => foldr((B n, List<A> xs) => Cons(Pair(m,n), xs))(ps, ns))(Nil, ms);


def List<Pair<A,B>> start<A,B>(List<A> ms, List<B> ns) = productP(ms,ns);

{

}