quicksort.scala

def qsort : Seq[Int] => Seq[Int] =
a => (a.size < 2) match {
  case true  => a
  case false =>
    val pivot = a(a.size / 2)
    qsort (
      a filter (pivot > _)) ++
      (a filter (pivot == _)) ++
      qsort (a filter (pivot < _)
    )
}