Provide a title on a value. If you can title polymorphically, please
instantiate Title_f instead of Title. Then you'll automatically
get a Title for each type instance, thanks to this rule.
instance Title_f f => Title (f a) where title = title_f
To handle ambiguity for types like ( Char) -- aka String, this
module is compiled with OverlappingInstances and
UndecidableInstances. The more specific instance (yours) wins.
In defining your instance, you might want to use the String instance,
e.g., title ttl "".