Sometimes, bounded enum types should be circular. Consider this enum type of directions:

data Direction  = North
                | East
                | South
                | West
                deriving (Eq, Enum, Bounded)

The Enum instance allows for succ North to be East and succ East to be South. But in this case, one would like to have some kind of succ with succ West = North again. With Eq and Bounded instances, the functions defined in this module act like circular versions of succ and pred.