MergeSort - classical sort algorithm done as refresh coding exercise

MergeSort.scala

object MergeSort {
  def mergeSort[T](list: List[T])(implicit order: Ordering[T]): List[T] = {
    def merge[T](l1: List[T], l2: List[T])(implicit order: Ordering[T]): List[T] = {
      (l1, l2) match {
        case (Nil, Nil) => Nil
        case (Nil, l) => l
        case (l, Nil) => l
        case (x :: tail1, y :: tail2) => if (order.compare(x, y) > 0) y :: merge(l1, tail2) else x :: merge(tail1, l2)
      }

    }
    list match {
      case Nil => Nil
      case x :: Nil => List(x)
      case l =>
        val (f, s) = l.splitAt(l.size / 2)
        merge(mergeSort(f), mergeSort(s))
    }

  } //> mergeSort: [T](list: List[T])(implicit order: Ordering[T])List[T]

  val l = List(1, 6, 5, 3, 6, 10, 91, 82, 73, 64, 55, 46, 37, 28, 19)
  //> l  : List[Int] = List(1, 6, 5, 3, 6, 10, 91, 82, 73, 64, 55, 46, 37, 28, 19)
  //| 
  mergeSort(l) //> res0: List[Int] = List(1, 3, 5, 6, 6, 10, 19, 28, 37, 46, 55, 64, 73, 82, 91
  //| )

}