Use List::Rotation::Cycle to loop through a list of values. Once you get to the end of the list, you go back to the beginning. List::Rotation::Cycle is implemented as a Singleton Pattern. You always just get 1 (the very same) Cycle object even if you use the new method several times. This is done by using Memoize on the new method. It returns the same object for every use of new that comes with the same List of parameters.