On Sun, May 25, 2014 at 12:49 AM, João Cristóvão <jmacristovao@gmail.com> wrote:

But my main point here is: should we limit generic deriving of
instances because some people don't see value in it for themselves,
given that some clearly do?

Yes, of course we should. The whole point of having typeclasses is that the instances should make sense for everyone. The bar for introducing both typeclasses and especially automatically derived instances is a whole lot higher than "works for me, sometimes".