// (* Richard Bird: Introduction to functional programming using Haskell, Section 7.2 *)

module RevFoldl;


def Acc foldlP<A,Acc>(f)(Acc z, List<A> xs) =
    case xs {
    Nil => z;
    Cons(x,xsP) => foldlP(f(z,x), xsP);
};


def List<A> prefix<A>(List<A> xs, A x) = Cons(x,xs);

def List<A> rev<A>(List<A> l) = foldlP(prefix)(Nil, l);

def List<A> start<A>(List<A> l) = rev(l);


{

}