arc> ; with ccc
  (time
    (with (x 0 y 0)
      (while (< x 1000000)
        (catch
          (when (odd x)
            (++ x)
            (throw))
          (++ y)
          (++ x)))
      (list x y)))
  time: 27208 msec.
  (1000000 500000)

  arc> ; without ccc
  (time
    (with (x 0 y 0)
      (while (< x 1000000)
        (if (odd x)
            (++ x)
            (do (++ y)
                (++ x))))
      (list x y)))
  time: 1978 msec.
  (1000000 500000)