module Data.Monoid.Monad.Writer.Lazy
( module Control.Monad.Writer.Lazy
, module Data.Monoid.Reducer
) where
import Control.Monad.Writer.Lazy
import Data.Monoid.Reducer
instance (Monoid w, Monoid m) => Monoid (Writer w m) where
mempty = return mempty
mappend = liftM2 mappend
instance (Monad m, Monoid w, Monoid n) => Monoid (WriterT w m n) where
mempty = return mempty
mappend = liftM2 mappend
instance (Monoid w, Monoid m) => Reducer m (Writer w m) where
unit = return
instance (Monad m, Monoid w, Monoid n) => Reducer n (WriterT w m n) where
unit = return
instance (Monad m, Monoid w, Monoid n) => Reducer (m n) (WriterT w m n) where
unit = lift