[Haskell-cafe] GHC 8.8 and MonadFail proposal

Hello, I built the GHC 8.8 branch and tried to use it. I was very surprised because many packages cannot be built due to the removal of the "fail" method from the Monad typeclass. GHC 8.6 (with -Wcompat) does not warn even if "fail" is defined. I had no chance to notice this change. Isn't this change too radical? The same thing happened in GHC 8.4 due to Semigroup. I could not notice this change beforehand because I did not know the "-Wcompat" option. In my opinion, we should have included "-Wcampat" in "-Wall". Anyway, if I understand correctly, "-Wcompat" does not help in the MonadFail case. I'm a fan of both proposal. But I feel that no period of warnings is not a good approach. --Kazu