Hi
* remove the MR entirely
Finally!
* adopt Monomorphic Pattern Bindings (MPB)
There are 6 reasons on that page why we shouldn't adopt MPB - of those number 5 I think is particularly compelling. There seems to be 1 main reason to remove it, which is that it has a complex translation to System F. That doesn't seem to be a particularly good reason at all! I'm guessing someone has written the translation so now applying consistently isn't that hard? Having x /= (x) is rather disturbing. Haskell has always had the attitude of doing what suits users, and making implementations work hard to handle the language features. In addition, this is a breaking change.
The nice thing about the combination of removing MR and adopting MPB is that we retain a way to explicitly declare monomorphic bindings. These are monomorphic bindings:
~x = e x@_ = e
If you really care, add a type signature. Given the tendancy for Hackage packages to have -Wall turned on and all warnings removed in patches (I'm sure half the people on Hackage have had a patch doing that from Gwern) I don't see a top-level type signature as being particularly problematic. In addition, both of those forms are non-obvious ways to declaring something monomorphic, and could easily be "cleaned up" by someone not appreciating the subtleties of sharing. Thanks Neil