sorting in scala

mergesort.scala

def mergesort(toSort: List[Int]) : List[Int] = {
  if(toSort.length<=1) toSort
  else{
    val (left, right) = split(toSort)
    merge(mergesort(left), mergesort(right))
  }
  def split(toSplit: List[Int]): (List[Int], List[Int]) = toSplit splitAt toSplit.length/2

  def merge(left: List[Int], right: List[Int]):List[Int] = {
    (left, right) match {
      case(Nil, right) => right
      case(left, Nil) => left
      case(leftHead::leftTail, rightHead::rightTail) =>
        if(leftHead<rightHead)leftHead::merge(leftTail, right)
        else rightHead :: merge(left, rightTail)
    }
  }
}
mergesort(List[Int](5,4,3,2,1))