2015-06-06 0:09 GMT+02:00 Anthony Cowley <acowley@seas.upenn.edu>:

This was stated unambiguously [...]

Looking back through the thread, this might be a bit of an exaggeration... ;-)

in the proposal and several times since
then, but, just to clarify: *there is no possible breakage from this
change*. In other words, the percentage of Haskell programs that will
break will not be "much, much higher." It will be 0%. [...]

OK, but even if we reach consensus that the change is worthwhile (for me it's not), it's still extremely important to make this a language extension which must be explicitly declared. Otherwise there *will* be heavy breakage through transitive dependencies, cabal not being able to find an install plan, etc. As was already noted, not everybody is using the latest and greatest GHC (often for a good reason).

So in a nutshell: -0.5 from me if it's a language extension, -1000 if it's on by default.