Re: [Haskell-cafe] Questions about the Functor class and it's use in "Data types à la carte"

On Dec 15, 2007 12:00 AM, David Menendez wrote:

These can (and, if Val is a newtype, will) be compiled to the same code, but they don't have the same type. In particular, there is no way to unify "a -> a" with "f a -> f b" for any f.

Thanks for noticing that! I hadn't seen before that the two Val constructors in fmap f (Val x) = Val x were of different types. Cheers, -- Felipe.