implementation of inorder scan of a binary tree

binary tree inorder

case class BT[T](left: Option[BT[T]], value: T, right: Option[BT[T]]);

def inorder[T](t:BT[T], out: T=>Unit): Unit = {
  val stack: mutable.Stack[(Boolean, BT[T])] = new mutable.Stack[(Boolean, BT[T])]()
  def p(n: BT[T]) = stack.push((false, n))
  p(t)
  while (!stack.isEmpty) {
    (stack.pop() match {
      case (true, top) =>
        out(top.value)
        top.right
      case (false, top) =>
        stack.push((true, top))
        top.left
    }) foreach p
  }
}