gistfile1.scala

 def balance(chars: List[Char]): Boolean = {
    val l = '('
    val r = ')'

    def helper(left: Int, right: Int, c: List[Char]): Boolean = {
      if (c.isEmpty)
        (left - right) == 0
      else {

        if (right > left) false
        else if (c.head == l) helper(left + 1, right, c.tail)
        else if (c.head == r) {
          helper(left, right + 1, c.tail)
        } else {
          helper(left, right, c.tail)
        }
      }
    }
    helper(0,0,chars)
  }