Safe Haskell	None
Language	Haskell2010

Algebra.Monad.Writer

Contents

The Writer monad
The Writer transformer
Keeping track of where we are
- Implementation
Orphan instances

Synopsis

The Writer monad

class (Monad m, Monoid w) => MonadWriter w m | m -> w where Source #

Minimal complete definition

tell, listen, censor

Methods

tell :: w -> m () Source #

listen :: m a -> m (w, a) Source #

censor :: m (a, w -> w) -> m a Source #

Instances

MonadWriter w m => MonadWriter w (Free m) Source #
Methods tell :: w -> Free m () Source # listen :: Free m a -> Free m (w, a) Source # censor :: Free m (a, w -> w) -> Free m a Source #
MonadWriter w m => MonadWriter w (ListT m) Source #
Methods tell :: w -> ListT m () Source # listen :: ListT m a -> ListT m (w, a) Source # censor :: ListT m (a, w -> w) -> ListT m a Source #
MonadWriter w m => MonadWriter w (TreeT m) Source #
Methods tell :: w -> TreeT m () Source # listen :: TreeT m a -> TreeT m (w, a) Source # censor :: TreeT m (a, w -> w) -> TreeT m a Source #
MonadWriter w m => MonadWriter w (MaybeT m) Source #
Methods tell :: w -> MaybeT m () Source # listen :: MaybeT m a -> MaybeT m (w, a) Source # censor :: MaybeT m (a, w -> w) -> MaybeT m a Source #
MonadWriter w m => MonadWriter w (StrictT m) Source #
Methods tell :: w -> StrictT m () Source # listen :: StrictT m a -> StrictT m (w, a) Source # censor :: StrictT m (a, w -> w) -> StrictT m a Source #
MonadWriter w m => MonadWriter w (LogicT m) Source #
Methods tell :: w -> LogicT m () Source # listen :: LogicT m a -> LogicT m (w, a) Source # censor :: LogicT m (a, w -> w) -> LogicT m a Source #
(Traversable f, Monad f, MonadWriter w g) => MonadWriter w (Compose' f g) Source #
Methods tell :: w -> Compose' f g () Source # listen :: Compose' f g a -> Compose' f g (w, a) Source # censor :: Compose' f g (a, w -> w) -> Compose' f g a Source #
MonadWriter w m => MonadWriter w (ReaderT r m) Source #
Methods tell :: w -> ReaderT r m () Source # listen :: ReaderT r m a -> ReaderT r m (w, a) Source # censor :: ReaderT r m (a, w -> w) -> ReaderT r m a Source #
MonadWriter w m => MonadWriter w (StateT s m) Source #
Methods tell :: w -> StateT s m () Source # listen :: StateT s m a -> StateT s m (w, a) Source # censor :: StateT s m (a, w -> w) -> StateT s m a Source #
(Monoid w, Monad m) => MonadWriter w (WriterT w m) Source #
Methods tell :: w -> WriterT w m () Source # listen :: WriterT w m a -> WriterT w m (w, a) Source # censor :: WriterT w m (a, w -> w) -> WriterT w m a Source #
(Monad m, SubSemi acc w, Monoid w) => MonadWriter w (CounterT w acc m) Source #
Methods tell :: w -> CounterT w acc m () Source # listen :: CounterT w acc m a -> CounterT w acc m (w, a) Source # censor :: CounterT w acc m (a, w -> w) -> CounterT w acc m a Source #
(Monad m, Monoid w) => MonadWriter w (RWST r w s m) Source #
Methods tell :: w -> RWST r w s m () Source # listen :: RWST r w s m a -> RWST r w s m (w, a) Source # censor :: RWST r w s m (a, w -> w) -> RWST r w s m a Source #
Ring t => MonadWriter (Product t) (ProbT t m) Source #
Methods tell :: Product t -> ProbT t m () Source # listen :: ProbT t m a -> ProbT t m (Product t, a) Source # censor :: ProbT t m (a, Product t -> Product t) -> ProbT t m a Source #

mute :: MonadWriter w m => m a -> m a Source #

intercept :: MonadWriter w m => m a -> m (w, a) Source #

intercept' :: MonadWriter w m => m a -> m w Source #

eavesdrop :: MonadWriter w m => m a -> m w Source #

The Writer transformer

data WriterT w m a Source #

A simple Writer monad

Instances

(Monad m, Monoid w, MonadFuture n m) => MonadFuture n (WriterT w m) Source #
Methods future :: n a -> WriterT w m a Source #
(Monoid w, Monad m) => MonadWriter w (WriterT w m) Source #
Methods tell :: w -> WriterT w m () Source # listen :: WriterT w m a -> WriterT w m (w, a) Source # censor :: WriterT w m (a, w -> w) -> WriterT w m a Source #
(Monoid w, MonadReader r m) => MonadReader r (WriterT w m) Source #
Methods ask :: WriterT w m r Source # local :: (r -> r) -> WriterT w m a -> WriterT w m a Source #
(Monoid w, MonadState r m) => MonadState r (WriterT w m) Source #
Methods get :: WriterT w m r Source # put :: r -> WriterT w m () Source # modify :: (r -> r) -> WriterT w m () Source #
Monoid w => ConcreteMonad (WriterT w) Source #
Methods generalize :: Monad m => WriterT w Id a -> WriterT w m a Source #
Monoid w => MonadTrans (WriterT w) Source #
Methods lift :: Monad m => m a -> WriterT w m a Source #
Monoid w => MonadInternal (WriterT w) Source #
Methods internal :: Monad m => (forall c. m (c, a) -> m (c, b)) -> WriterT w m a -> WriterT w m b Source #
(Monoid w, Unit m) => Unit (WriterT w m) Source #
Methods pure :: a -> WriterT w m a Source #
(MonadCont m, Monoid w) => MonadCont (WriterT w m) Source #
Methods callCC :: (forall b. (a -> WriterT w m b) -> WriterT w m b) -> WriterT w m a Source #
(MonadList m, Monoid w) => MonadList (WriterT w m) Source #
Methods choose :: [a] -> WriterT w m a Source #
(MonadFix m, Monoid w) => MonadFix (WriterT w m) Source #
Methods mfix :: (a -> WriterT w m a) -> WriterT w m a Source #
Traversable m => Traversable (WriterT e m) Source #
Methods sequence :: Applicative f => WriterT e m (f a) -> f (WriterT e m a) Source #
Foldable m => Foldable (WriterT w m) Source #
Methods fold :: Monoid m => WriterT w m m -> m Source #
(Monoid w, Monad m) => Monad (WriterT w m) Source #
Methods join :: WriterT w m (WriterT w m a) -> WriterT w m a Source # (>>=) :: WriterT w m a -> (a -> WriterT w m b) -> WriterT w m b Source #
(Monad m, Monoid w) => Applicative (WriterT w m) Source #

(Monad m, Monoid w) => SemiApplicative (WriterT w m) Source #
Methods (<*>) :: WriterT w m (a -> b) -> WriterT w m a -> WriterT w m b Source #
Functor m => Functor (WriterT w m) Source #
Methods map :: (a -> b) -> WriterT w m a -> WriterT w m b Source #
(Monoid w, MonadLogic m l) => MonadLogic (WriterT w m) (WriterT w l) Source #
Methods deduce :: WriterT w l a -> WriterT w m (Maybe (a, WriterT w l a)) Source # induce :: WriterT w m (Maybe (a, WriterT w l a)) -> WriterT w l a Source #
Ring (m (a, Void, w)) => Ring (WriterT w m a) Source #
Methods one :: WriterT w m a Source #
Semiring (m (a, Void, w)) => Semiring (WriterT w m a) Source #
Methods (*) :: WriterT w m a -> WriterT w m a -> WriterT w m a Source #
Monoid (m (a, Void, w)) => Monoid (WriterT w m a) Source #
Methods zero :: WriterT w m a Source #
Semigroup (m (a, Void, w)) => Semigroup (WriterT w m a) Source #
Methods (+) :: WriterT w m a -> WriterT w m a -> WriterT w m a Source #

type Writer w a = WriterT w Id a Source #

writerT :: (Functor m, Functor m') => Iso (WriterT w m a) (WriterT w' m' b) (m (w, a)) (m' (w', b)) Source #

writer :: Iso (Writer w a) (Writer w' b) (w, a) (w', b) Source #

pureWriter :: Monoid w => Iso (w, a) (w', b) a b Source #

Keeping track of where we are

class (SubSemi acc w, MonadWriter w m) => MonadCounter w acc m | m -> acc where Source #

Minimal complete definition

getCounter, setCounter

Methods

getCounter :: m acc Source #

setCounter :: acc -> m () Source #

Instances

MonadCounter w a m => MonadCounter w a (Free m) Source #
Methods getCounter :: Free m a Source # setCounter :: a -> Free m () Source #
MonadCounter w acc m => MonadCounter w acc (ReaderT r m) Source #
Methods getCounter :: ReaderT r m acc Source # setCounter :: acc -> ReaderT r m () Source #
MonadCounter w acc m => MonadCounter w acc (StateT s m) Source #
Methods getCounter :: StateT s m acc Source # setCounter :: acc -> StateT s m () Source #
(Monad m, Monoid w, SubSemi acc w) => MonadCounter w acc (CounterT w acc m) Source #
Methods getCounter :: CounterT w acc m acc Source # setCounter :: acc -> CounterT w acc m () Source #

Implementation

data CounterT w acc m a Source #

The canonical representsation of a WriterAcc Monad

Instances

(Monad m, Monoid w, SubSemi acc w) => MonadCounter w acc (CounterT w acc m) Source #
Methods getCounter :: CounterT w acc m acc Source # setCounter :: acc -> CounterT w acc m () Source #
(Monad m, Monoid w, MonadFuture n m) => MonadFuture n (CounterT w acc m) Source #
Methods future :: n a -> CounterT w acc m a Source #
(Monad m, SubSemi acc w, Monoid w) => MonadWriter w (CounterT w acc m) Source #
Methods tell :: w -> CounterT w acc m () Source # listen :: CounterT w acc m a -> CounterT w acc m (w, a) Source # censor :: CounterT w acc m (a, w -> w) -> CounterT w acc m a Source #
(MonadState s m, Monoid w) => MonadState s (CounterT w acc m) Source #
Methods get :: CounterT w acc m s Source # put :: s -> CounterT w acc m () Source # modify :: (s -> s) -> CounterT w acc m () Source #
Monoid w => ConcreteMonad (CounterT w acc) Source #
Methods generalize :: Monad m => CounterT w acc Id a -> CounterT w acc m a Source #
Monoid w => MonadTrans (CounterT w acc) Source #
Methods lift :: Monad m => m a -> CounterT w acc m a Source #
(Monoid w, Unit m) => Unit (CounterT w acc m) Source #
Methods pure :: a -> CounterT w acc m a Source #
(MonadFix m, Monoid w) => MonadFix (CounterT w acc m) Source #
Methods mfix :: (a -> CounterT w acc m a) -> CounterT w acc m a Source #
(Monoid w, Monad m) => Monad (CounterT w a m) Source #
Methods join :: CounterT w a m (CounterT w a m a) -> CounterT w a m a Source # (>>=) :: CounterT w a m a -> (a -> CounterT w a m b) -> CounterT w a m b Source #
(Monad m, Monoid w) => Applicative (CounterT w acc m) Source #

(Monad m, Monoid w) => SemiApplicative (CounterT w acc m) Source #
Methods (<*>) :: CounterT w acc m (a -> b) -> CounterT w acc m a -> CounterT w acc m b Source #
Functor m => Functor (CounterT w acc m) Source #
Methods map :: (a -> b) -> CounterT w acc m a -> CounterT w acc m b Source #

type Counter w acc a = CounterT w acc Id a Source #

i'counterT :: (SubSemi acc w, Monoid acc', Functor m) => Iso (CounterT w acc m a) (CounterT w' acc' m' a') (m (a, acc, w)) (m' (a', acc', w')) Source #

i'counter :: (SubSemi acc w, Monoid acc') => Iso (Counter w acc a) (Counter w' acc' a') (a, acc, w) (a', acc', w') Source #

Orphan instances

Monoid w => MonadWriter w ((,) w) Source #
Methods tell :: w -> (w, ()) Source # listen :: (w, a) -> (w, (w, a)) Source # censor :: (w, (a, w -> w)) -> (w, a) Source #