regression/once.sml

   1 open SMLofNJ.Cont
   2
   3 val r: unit cont option ref = ref NONE
   4
   5 val a = ref 13
   6
   7 val () = callcc(fn k => r := SOME k)
   8
   9 val b = ref 13
  10
  11 val _ = a := !a - 1
  12 val _ = b := !b - 1
  13
  14 val _ = print(concat["a = ", Int.toString(!a),
  15                      "  b = ", Int.toString(!b),
  16                      "\n"])
  17
  18 val _ = if !a = 0
  19            then ()
  20         else throw (valOf(!r)) ()