On Fri, Sep 4, 2009 at 4:55 PM, Taral<taralx at gmail.com> wrote: > Oh, those. I think there's some optimizer trickery to rewrite (mappend > x mempty) to x. Or not. Looks like that's only for builtin monoids. -- Taral <taralx at gmail.com> "Please let me know if there's any further trouble I can give you." -- Unknown