[Haskell-beginners] Haskell wants the type, but I only know the class.

[Amy de Buitléir]

Thank you, David and Antoine.

I was planning to have files containing different types of objects, but where
all of the types are instances of a particular class. Since the class definition
ensures that whatever the types are, they implement the methods that I need, I
hoped to be able to manipulate the files using those methods, without having to
find out the class programmatically.

Clearly I need to rethink this. I'm looking into existentially quantified data
constructors now, maybe that will help.