Tail recurive version of length

TailRecursiveListLength.scala

object TailRecursiveListLength {
   def trlength(l: List[Int], counter: Int): Int = l match {
      case Nil => counter
      case x :: xs => trlength(xs, counter + 1)
   }
   def main(args: Array[String]) {
      println("Length of list () is: " + trlength(List(), 0))
      println("Length of list (1,6,2,5,8,93) is: " + trlength(List(1,6,2,5,8,93), 0))
      
   }
}