-1 from me. First, I think people should be discouraged from using tuples. Tuples for anything but very short-lived structures (like returning multiple results from a function) make code very unmaintainable. Instead hand-rolled records are the tool of choice, for which you can define your functor instance as you see fit. Second, it is confusing that fmap (+1) (1,2,3) = (1,2,4) while fmap (+1) [1,2,3] = [2,3,4] --Andreas On 18.01.2016 21:10, David Feuer wrote:
For some reason I really can't imagine, it seems the only tuple type with a Functor instance is (,) a. I was astonished to find that
fmap (+1) (1,2,3)
doesn't work. Since this is *useful*, and there is *only one way to do it*, I propose we add the following:
instance Functor ((,,) a b) where fmap f (a,b,c) = (a,b,f c) instance Functor ((,,,) a b c) where fmap f (a,b,c,d) = (a,b,c,f d) etc.
I would really love to see these make 8.0.0, but if that's impossible then so be it. _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
-- Andreas Abel <>< Du bist der geliebte Mensch. Department of Computer Science and Engineering Chalmers and Gothenburg University, Sweden andreas.abel@gu.se http://www2.tcs.ifi.lmu.de/~abel/