On Tue, 27 Jan 2015, Herbert Valerio Riedel wrote:
Ironically, the AMP-related warnings in GHC 7.8 weren't very effective at getting noticed timely in order to have Hackage ready for the actual AMP-changes occurring in GHC 7.10. By far the most breakages[1] I encountered (and reported) over the last weeks in popularly-depended-upon packages were due to missing Functor/Applicative instances. It'd be interesting to know why those warnings weren't acted upon during 2014.
Otoh, I don't have numbers how many packages were actually fixed up *thanks* to the GHC 7.8 warnings...
I have added Applicative instances whereever suggested by GHC-7.8, but I have not recompiled all my packages since then and I have not released all updated packages. Maybe a year is just too short?