[Haskell-cafe] Breaking change to Eq accepted by Core Libraries Committee

[Olaf Klinke]

For what it's worth, one of the examples listed in the issue where (/=)
is not simply the negation of (==) is violating the laws. It is the one
in 
https://hackage.haskell.org/package/numbers-3000.2.0.2/docs/Data-Number-Interval.html
That module defines two intervals to be equal if their bounds are
equal, but to be unequal only if they are disjoint. In my eyes this
speaks for the proposal, because the library author would have been
unable to write the broken instance.  

(And I did look at the proposal some time ago, whence I feel it was
indeed discussed or at least mentioned on this list before.) 

Olaf