QuickSort.scala

def partition[T <% Ordered[T]](elm: T, list: List[T]): (List[T], List[T]) = {
  doPartition(elm, list, Nil, Nil)

  def doPartition[T <% Ordered[T]](elm: T, list: List[T], smallerItems: List[T], largerItems: List[T]): (List[T], List[T]) =
    list match {
      case Nil => (smallerItems, largerItems)
      case head :: tail =>
        if (head < elm)
          doPartition(elm, tail, head :: smallerItems, largerItems)
        else
          doPartition(elm, tail, smallerItems, head :: largerItems)
    }
}

def quickSort[T <% Ordered[T]](data: List[T]): List[T] =
  data match {
    case Nil          => Nil
    case head :: Nil  => List(head)
    case head :: tail =>
      val (list1, list2) = partition(head, tail)
      val smallerList = quickSort(list1)
      val biggerList = quickSort(list2)
      smallerList ::: (head :: biggerList)
  }