lambda-hacker

//  Immutable Stack Type using List

class Stack[A] (val elems: List[A] = List.empty[A]) {

  def push(v: A) : Stack[A] = new Stack(v :: elems)
  def pushAll(xs: Iterable[A]) : Stack[A] =
           xs.foldLeft (this) ((accStack, e) => accStack.push(e))

  def pop()  : Stack[A] = new Stack(elems.tail)
  def pop2() : (A, Stack[A]) = (elems.head, new Stack(elems.tail))