Safe Haskell | None |
---|---|
Language | Haskell2010 |
- class (Monoid w, Monad m) => MonadWriter tag w m | m tag -> w where
- listens :: MonadWriter tag w m => proxy tag -> (w -> b) -> m a -> m (a, b)
- censor :: MonadWriter tag w m => proxy tag -> (w -> w) -> m a -> m a
Documentation
class (Monoid w, Monad m) => MonadWriter tag w m | m tag -> w where Source
See MonadWriter
.
writer :: proxy tag -> (a, w) -> m a Source
Embed a simple writer action.
tell :: proxy tag -> w -> m () Source
Append a value to the accumulator within the monad.
listen :: proxy tag -> m a -> m (a, w) Source
Execute an action and add its accumulator to the value of the computation.
pass :: proxy tag -> m (a, w -> w) -> m a Source
Execute an action which returns a value and a function, and return the value, applying the function to the accumulator.
MonadWriter tag w m => MonadWriter tag w (MaybeT m) Source | |
MonadWriter tag w m => MonadWriter tag w (IdentityT m) Source | |
(Monoid w', MonadWriter tag w m) => MonadWriter tag w (WriterT w' m) Source | |
MonadWriter tag w m => MonadWriter tag w (StateT s m) Source | |
MonadWriter tag w m => MonadWriter tag w (StateT s m) Source | |
MonadWriter tag w m => MonadWriter tag w (ReaderT r m) Source | |
MonadWriter tag w m => MonadWriter tag w (ExceptT e m) Source | |
MonadWriter tag w m => MonadWriter tag w (WrappedEther tag' m) Source | |
MonadWriter tag w m => MonadWriter tag w (StateT tag' e m) Source | |
MonadWriter tag w m => MonadWriter tag w (StateT tag' e m) Source | |
MonadWriter tag w m => MonadWriter tag w (ExceptT tag' e m) Source | |
MonadWriter tag w m => MonadWriter tag w (ReaderT tag' r m) Source | |
(Monoid w', MonadWriter tag w m) => MonadWriter tag w (WriterT tag' w' m) Source | |
(Monoid w, Monad m) => MonadWriter tag w (WriterT tag w m) Source |
listens :: MonadWriter tag w m => proxy tag -> (w -> b) -> m a -> m (a, b) Source
Execute an action and add the result of applying the given function to its accumulator to the value of the computation.
censor :: MonadWriter tag w m => proxy tag -> (w -> w) -> m a -> m a Source
Execute an action and apply a function to its accumulator.