I propose adding an (orphan) instance of Monad for ((,) e) to Data.Monoid. Discussion deadline: 2 weeks from now (November 26) == Current State == No instance == The Issues == Control.Applicative already exports a compatible instance for Applicative for ((,) e), but there isn't a canonical place to get the compatible Monad. == Proposed enhancement == Add the following orphan instance to Data.Monoid. instance Monoid e => Monad ((,) e) where return a = (a, mempty) (w,a) >>= k = (mappend w w', b) where (w',b) = k a Why? Monoid isn't exported from the Prelude, so there is currently no place for this instance to live currently that doesn't render it an orphan. == Alternative == We could place this instance in Control.Monad.Instances which is where we've placed similar instances in the past. However, this would increase the likelihood of failure to properly import the instance for users, who would have to know to import both Data.Monoid and Control.Monad.Instances, rather than just Data.Monoid. Moreover in a separate active proposal I've just proposed moving all the Control.Monad.Instances instances out, so in the event that that proposal is adopted this would be unsatisfyingly the only instance there. -Edward