[ char [ over of
    swap
    char ] swap of
    join shuffle ]      is bracket$ ( n --> $ )

  [ 0 swap witheach
      [ char [ =
        iff 1 else -1 +
        dup 0 < if
          conclude ]
    0 = ]               is balanced ( $ --> b )


  10 times
    [ 20 i 2 * - times sp
      i bracket$ dup echo$
      say " is "
      balanced not if
        [ say "un" ]
      say "balanced."
      cr ]