[Haskell-cafe] Re: Type classes question

Ryan Ingram writes:

[...]

Here's another possible solution:

...

newtype AsFunctor s a = AF { fstream :: (s a) } instance (Stream f) => Functor (AsFunctor f) where fmap f (AF s) = AF (fmapStreamDefault f s)

Now to use fmap you wrap in AF and unwrap with fstream.

None of the existing solutions are really satisfactory, unfortunately.

Bulat Ziganshin writes:

http://haskell.org/haskellwiki/OOP_vs_type_classes may be useful

Many thanks to you both for the clarification and pointers. cheers, Roly