countable

class Countable, for countable types class AtLeastOneCountable, for countable types that have at least one value class InfiniteCountable, for infinite countable types class Searchable, for types that can be searched over. This turns out to include some infinite types, see http://math.andrej.com/2007/09/28/seemingly-impossible-functional-programs/. class Finite, for finite types class Empty, for empty types data Nothing, an empty type Some orphan instances: (Searchable a,Eq b) => Eq (a -> b) (Finite t) => Foldable ((->) t) (Finite a) => Traversable ((->) a) (Show a,Finite a,Show b) => Show (a -> b)