-- | The multi-valued version of mtl's MonadWriter module Control.Monad.Trans.MultiWriter.Class ( -- * MonadMultiWriter class MonadMultiWriter(..) ) where import Control.Monad.Trans.Class ( MonadTrans , lift ) import Data.Monoid -- TODO: some haddock class (Monad m, Monoid a) => MonadMultiWriter a m where mTell :: a -> m () instance (MonadTrans t, Monad (t m), MonadMultiWriter a m) => MonadMultiWriter a (t m) where mTell = lift . mTell