Scala : Determine whether parentheses are balanced within a string

balanced.scala

 def balance(chars: List[Char]): Boolean = {

   val onlyBrackets = chars.filter(c => '('.equals(c) || ')'.equals(c))

  @tailrec
  def isBalanced(status : Int, chars : List[Char]) : Boolean = {
     if(chars.isEmpty) status == 0
     else status >= 0 && isBalanced({if(chars.head == ')') status - 1 else status + 1}, chars.tail)
  }

  onlyBrackets.size % 2 == 0 && isBalanced(0,onlyBrackets)
 }