Hi, I'm facing the following problem. I've got come computation c :: a -> Reader e b that i'm running on several as: mapM c xs A natural optimisation of this program would to be to take advantage of Control.Parallel to run these computation in parallel, which seems sound since the Reader monad is commutative. Unfortunately, I didn't manage to do so. Has this situation been tackled with before ? Is there some library or function I've missed involving commutative monads and Control.Parallel ? Regards, Paul