module PrependAll;


// def List<A> append<A>(List<A> l1, List<A> l2) =
//     case l1 {
//     Nil => l2;
//     Cons(x,xs) => Cons(x, append(xs, l2));
// };


// def List<List<A>> prependAll<A>(List<A> xs, List<List<A>> ys) = map((List<A> s) => append(xs,s))(ys);


// let rec append xs ys =
//   match xs with
//   | [] -> ys
//   | x :: xs' -> x :: (append xs' ys)
// ;;

def List<A> append<A>(List<A> xs, List<A> ys) =
    case xs {
    Nil => ys;
    Cons(x,xsP) => Cons(x, append(xsP, ys));
};

def List<List<A>> prependAll(List<A> xs, List<List<A>> ys) = map((List<A> bs) => append(xs,bs))(ys);


def List<List<A>> start(List<A> xs, List<List<A>> ys) = prependAll(xs,ys);

{

}