Portability  nonportable (multiparam classes, functional dependencies) 

Stability  experimental 
Maintainer  libraries@haskell.org 
Lazy writer monads.
Inspired by the paper /Functional Programming with Overloading and HigherOrder Polymorphism/, Mark P Jones (http://web.cecs.pdx.edu/~mpj/pubs/springschool.html) Advanced School of Functional Programming, 1995.
Documentation
module Control.Monad.Writer.Class
execWriter :: Writer w a > wSource
WriterT  

(Monoid w, Monad m) => MonadWriter w (WriterT w m)  
(Monoid w, MonadError e m) => MonadError e (WriterT w m)  
(Monoid w, MonadState s m) => MonadState s (WriterT w m)  
(Monoid w, MonadReader r m) => MonadReader r (WriterT w m)  
Monoid w => MonadTrans (WriterT w)  
(Monoid w, Monad m) => Monad (WriterT w m)  
Monad m => Functor (WriterT w m)  
(Monoid w, MonadFix m) => MonadFix (WriterT w m)  
(Monoid w, MonadPlus m) => MonadPlus (WriterT w m)  
(Monoid w, MonadIO m) => MonadIO (WriterT w m)  
(Monoid w, MonadCont m) => MonadCont (WriterT w m) 
execWriterT :: Monad m => WriterT w m a > m wSource
mapWriterT :: (m (a, w) > n (b, w')) > WriterT w m a > WriterT w' n bSource
module Control.Monad
module Control.Monad.Fix
module Control.Monad.Trans
module Data.Monoid