| Portability | non-portable (type families) |
|---|---|
| Stability | experimental |
| Maintainer | ross@soi.city.ac.uk |
| Safe Haskell | Safe-Inferred |
Control.Monad.Writer.Class
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 (WriterType m), Monad m) => MonadWriter m whereSource
Associated Types
type WriterType m Source
Methods
tell :: WriterType m -> m ()Source
listen :: m a -> m (a, WriterType m)Source
pass :: m (a, WriterType m -> WriterType m) -> m aSource
Instances
| MonadWriter m => MonadWriter (MaybeT m) | |
| MonadWriter m => MonadWriter (IdentityT m) | |
| (Monoid w, Monad m) => MonadWriter (WriterT w m) | |
| (Monoid w, Monad m) => MonadWriter (WriterT w m) | |
| MonadWriter m => MonadWriter (StateT s m) | |
| MonadWriter m => MonadWriter (StateT s m) | |
| MonadWriter m => MonadWriter (ReaderT r m) | |
| (Error e, MonadWriter m) => MonadWriter (ErrorT e m) | |
| (Monoid w, Monad m) => MonadWriter (RWST r w s m) | |
| (Monoid w, Monad m) => MonadWriter (RWST r w s m) |
listens :: MonadWriter m => (WriterType m -> b) -> m a -> m (a, b)Source
censor :: MonadWriter m => (WriterType m -> WriterType m) -> m a -> m aSource