use "lazy_lists.sml";

fun odometerNextState []      = NONE
  | odometerNextState (x::xs) =
    if x = 5 then
        case odometerNextState xs of
             NONE   => NONE
           | SOME v => SOME (1::v)
    else
        SOME ((x+1)::xs);

fun odometerList NONE         = LazyNil
  | odometerList (SOME state) =
    LazyCons (state, fn () => odometerList (odometerNextState state));

val finiteOdometer = odometerList (SOME [1,1,1,1,1]);