module RevDl;

def B comp<A,B>(f, g)(A x) = f(g(x)) ;

def A id<A>(A x) = x;


//(* walk :: list -> (list -> list) *)
def B walk<A,B>(List<A> xs) =
    case xs {
    Nil => id;                  // Higher-order constructs are not supported by abs!
    Cons(x, xsP) => ((A a) => comp(wal(xsP), ((List<A> ys) => Cons(x,ys)))(a));
};


// (* rev :: list -> list *)
// def List<A> rev<A>(List<A> l) =

//   in walk l Nil

{

}