Re: [Haskell-cafe] Using fundeps to resolve polymorphic types to concrete types

...

But if you have actual values rather than just unit types, note that this won't work:

...

instance DeriveType A B where someDestructor (SomeConstructor _ b) = b

I couldn't understand the sentence "actual values rather than unit types". What do you have in mind?

I didn't pay attention to the |b| value returned. So what you meant was that only a constant function will do, not a function that returns the value |b|. P.