"Case analysis" functions are those which take one function for each constructor of a sum type, examine a value of that type, and call the relevant function depending on which constructor was used to build that type. Examples include
maybe,
either and
bool. generic-case gives you these functions for any type which implements Generic from generics-sop.
maybe :: forall a r. r -> (a -> r) -> Maybe a -> r
maybe = gcaseR @(Maybe a)For more detailed documentation, see Generics.Case.