Hi, I was expanding on my earlier learning, to try a triple monad stack: {-# LANGUAGE GeneralizedNewtypeDeriving #-} <...snip...> import System.Random import Control.Monad.Random import Control.Monad.State.Lazy import Control.Monad.Reader newtype ReaderStateRandom r s g a = RSR { rSR :: ReaderT r (StateT s (Rand g)) a } deriving (Monad, MonadReader r, MonadState s) However, it seems that I must implement MonadRandom myself, as there is no instance for this sort of arrangement already. Probably this is trivial, but I'm having trouble wrapping my mind around how to do it. Would anybody perhaps assist me in implementing one function, to help guide me in the correct direction? instance MonadRandom (ReaderStateRandom r s g) where getRandom = ...? -- http://justonemoremathproblem.com To protect my privacy, please use PGP encryption. It's free and easy to use! My public key ID is 0x340EA95A (pgp.mit.edu).