Exercise 2: Parentheses Balancing

balance.sc

object balance {

  def balance(chars: List[Char]): Boolean = {
    def loop(acc: Int, list: List[Char]): Int =
      if (list.isEmpty) acc
      else if (list.head == '(') loop(acc + 1, list.tail)
      else if (list.head == ')' && acc > 0) loop(acc - 1, list.tail)
      else if (list.head == ')' && acc <= 0) -1
      else loop(acc, list.tail)
    loop(0, chars) == 0
  }

  balance("()".toList)
  balance(")(".toList)
  balance("xxx".toList)
  balance(List())
  balance("".toList)
  balance("(if (zero? x) max (/ 1 x))".toList)
  balance("I told him (that it's not (yet) done).\n(But he wasn't listening)".toList)
  balance(":-)".toList)
  balance("())(".toList)
  balance("(".toList)

}

This strategy is so much simpler than mine cries dramatically