mergesort in scala

gistfile1.scala

val r = new scala.util.Random()             
val data = List.fill(10)(r.nextInt(100))

def msort(data: List[Int]): List[Int] = {
    def merge(xs: List[Int], ys: List[Int]): List[Int] = (xs, ys) match {
      case (List(), _) => ys
      case (_, List()) => xs
      case (x :: xs1, y :: ys1) => if (x < y) x :: merge(xs1, ys) else y :: merge(xs, ys1)
    }

    val n = data.length / 2
    if (n == 0)
      data
    else {
      val (first, second) = data.splitAt(n)
      merge(msort(first), msort(second))
    }
}                                             

msort(data)