I'd like to avoid situations where adding a LANGUAGE pragma changes the semantics of code Is this one? On 12.06.2015 03:49, Henning Thielemann wrote:
On Thu, 11 Jun 2015, Edward Kmett wrote:
I personally strongly believe in keeping the Applicative and Monad for a type compatible. Otherwise why the heck did we make Applicative a superclass of Monad?
I was extending the thought of treating a list like it would have ZipList semantics. I thought loudly about what I would have done if I could re-invent Haskell 98. If list would have an Applicative instance with ZipList semantics then it would not have a Monad instance, at all.
In this case the thing David wants only makes any difference if you explicitly turn on OverloadedLists, so if you never use that extension you'll never care about the instance anyways.
When I speak about surprises then I mean the situation where I read code of others, since I am not as much surprised about my own code. In this case someone else has enabled OverloadedLists. _______________________________________________ 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/