IMPLEMENTATION QuickSort

IMPORT Nat COMPLETELY
IMPORT Seq[nat] COMPLETELY

-- Unsortierte Sequenz zu Testzwecken
FUN testSeq : seq[nat]
DEF testSeq == %(5,7,6,4,8,3,9,2) ++ %(0,1,10)

DEF quickSort(<>) == <>
DEF quickSort(a::R) == LET sm ==      (_ < a)|R
                           me == a :: (_ = a)|R
                           la ==      (_ > a)|R
                       IN quickSort(sm) ++ me ++ quickSort(la)