Haskell Hierarchical Libraries (mtl package)Source codeContentsIndex
Control.Monad.Writer.Class
Portabilitynon-portable (multi-param classes, functional dependencies)
Stabilityexperimental
Maintainerlibraries@haskell.org
Description

The MonadWriter class.

Inspired by the paper Functional Programming with Overloading and Higher-Order Polymorphism, Mark P Jones (http://web.cecs.pdx.edu/~mpj/pubs/springschool.html) Advanced School of Functional Programming, 1995.

Documentation
class (Monoid w, Monad m) => MonadWriter w m | m -> w where
Methods
tell :: w -> m ()
listen :: m a -> m (a, w)
pass :: m (a, w -> w) -> m a
show/hide Instances
Monoid w => MonadWriter w (Writer w)
Monoid w => MonadWriter w (Writer w)
(Error e, MonadWriter w m) => MonadWriter w (ErrorT e m)
MonadWriter w m => MonadWriter w (ReaderT r m)
MonadWriter w m => MonadWriter w (StateT s m)
MonadWriter w m => MonadWriter w (StateT s m)
(Monoid w, Monad m) => MonadWriter w (WriterT w m)
(Monoid w, Monad m) => MonadWriter w (WriterT w m)
Monoid w => MonadWriter w (RWS r w s)
Monoid w => MonadWriter w (RWS r w s)
(Monoid w, Monad m) => MonadWriter w (RWST r w s m)
(Monoid w, Monad m) => MonadWriter w (RWST r w s m)
listens :: MonadWriter w m => (w -> b) -> m a -> m (a, b)
censor :: MonadWriter w m => (w -> w) -> m a -> m a
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