(function "cmp" (i: int j: int)
  (- i j))

(function "quick" (lo: int hi: int a: addr cmp: addr)
  (if (< lo hi)
      (let (i lo
            j hi
            pivot (addraref a hi))
        (while (< i j)
          (while (if (< i hi) (<= (app cmp [(addraref a i) pivot] int) 0) 0)
            (assign i (+ i 1)))
          (while (if (> j lo) (>= (app cmp [(addraref a j) pivot] int) 0) 0)
            (assign j (- j 1)))
          (if (< i j)
              (let temp (addraref a i)
                   (addraset a i (addraref a j))
                   (addraset a j temp))
            []))
        (let temp (addraref a i)
             (addraset a i (addraref a hi))
             (addraset a hi temp))
        (app "quick" [lo (- i 1) a cmp] unit)
        (app "quick" [(+ i 1) hi a cmp] unit))
    []))

(function "quicksort" (lo: int hi: int a: addr)
  (app "quick" [lo hi a "cmp"] unit))