And to forestall the weirdness we ran into with <*> vs. ap, I think GHC 7.12 should give multi-page flashing colored warnings when it sees a Semigroup instance whose definition calls mappend or the non-semigroup version of <>.
On 2015-03-29 at 17:23:19 +0200, David Feuer wrote:
> I guess I should get a dog in the fight—I think <> should be the Semigroup
> method.
+1