Edward A Kmett
Sadly, I've mostly given up on even convincing folks to refactor Monoid to pull out Semigroup which I view pragmatically as a prerequisite to including something like Apply or Bind in a serious hierarchy reform proposal.
When someone raised adding Semigroup during the (<>) = mappend proposal the idea was quickly derided and dismissed.
btw, I didn't have the impression that it was "derided" but the issue seemed to be (iirc -- please correct me if I got it wrong) that adding 'Semigroup' as a separate typeclass would break code, as it would require to replace occurences of the constraint 'Monoid a =>' to '(Monoid a, Semigroup a) =>', and for some reason I don't recall right now making Semigroup a superclass of Monoid wasn't an option either. IMHO, if we have a Monoid class in the standard/base libraries, we should have a Semigroup class as well there sooner or later... cheers, hvr