Am Montag, 9. Januar 2006 19:42 schrieb Twan van Laarhoven: > [...] > But why is not every instance of MonadPlus also an instance of Monoid? > > > instance MonadPlus m => Monoid (m a) where > > mempty = mzero > > mappend = mplus I think that this is not legal Haskell 98. > [...] Best wishes, Wolfgang