Modulererebase-1.21.2Haskell2010

Control.Monad.RWS.Class

4 classes
6 values

Packagererebase-1.21.2
Exports10
LanguageHaskell2010
LicenceMIT
SourceClass.hs

valueasks

:: MonadReader r m
=> (r -> a)
The selector function to apply to the environment.
-> m a

Retrieves a function of the current environment.

valuegets :: MonadState s m => (s -> a) -> m a

Gets specific component of the state, using a projection function supplied.

valuemodify :: MonadState s m => (s -> s) -> m ()

Monadic state transformer.

Maps an old state to a new state inside a state monad. The old state is thrown away.

     Main> :t modify ((+1) :: Int -> Int)
     modify (...) :: (MonadState Int a) => a ()

This says that modify (+1) acts over any Monad that is a member of the MonadState class, with an Int state.

valuemodify' :: MonadState s m => (s -> s) -> m ()

A variant of modify in which the computation is strict in the new state.

valuecensor :: MonadWriter w m => (w -> w) -> m a -> m a

censor f m is an action that executes the action m and applies the function f to its output, leaving the return value unchanged.

censor f m = pass (liftM (\x -> (x,f)) m)

valuelistens :: MonadWriter w m => (w -> b) -> m a -> m (a, b)

listens f m is an action that executes the action m and adds the result of applying f to the output to the value of the computation.

listens f m = liftM (id *** f) (listen m)

classclass Monad m => MonadReader r (m :: Type -> Type) | m -> r where

See examples in Control.Monad.Reader. Note, the partially applied function type (->) r is a simple reader monad. See the instance declaration below.

Methods

ask :: m r
Retrieves the monad environment.
local :: (r -> r) -> m a -> m a
Executes a computation in a modified environment.
reader :: (r -> a) -> m a
Retrieves a function of the current environment.

Instances29MonadReader, …

MonadReader e m => MonadReader e (CatchT m)Defined in exceptions-0.10.9 · Control.Monad.Catch.Pure
MonadReader e m => MonadReader e (Free m)Defined in free-5.2 · Control.Monad.Free
MonadReader e m => MonadReader e (Free m)Defined in free-5.2 · Control.Monad.Free.Ap
MonadReader e m => MonadReader e (F m)Defined in free-5.2 · Control.Monad.Free.Church
MonadReader e m => MonadReader e (IterT m)Defined in free-5.2 · Control.Monad.Trans.Iter
MonadReader r m => MonadReader r (MaybeT m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
(Representable f, Rep f ~ a) => MonadReader a (Co f)Defined in adjunctions-4.4.3 · Data.Functor.Rep
Monad m => MonadReader r (ReaderT r m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
MonadReader r m => MonadReader r (FT f m)Defined in free-5.2 · Control.Monad.Trans.Free.Church
MonadReader r m => MonadReader r (ExceptT e m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
MonadReader r m => MonadReader r (IdentityT m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
MonadReader r m => MonadReader r (StateT s m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
MonadReader r m => MonadReader r (StateT s m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
MonadReader r' m => MonadReader r' (SelectT r m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
(Representable f, Monad m, Rep f ~ e) => MonadReader e (ReaderT f m)Defined in adjunctions-4.4.3 · Control.Monad.Representable.Reader
(Representable g, MonadReader e m) => MonadReader e (StateT g m)Defined in adjunctions-4.4.3 · Control.Monad.Representable.State
(Applicative f, MonadReader r m) => MonadReader r (FreeT f m)Defined in free-5.2 · Control.Monad.Trans.Free.Ap
(Functor f, MonadReader r m) => MonadReader r (FreeT f m)Defined in free-5.2 · Control.Monad.Trans.Free
(Monoid w, MonadReader r m) => MonadReader r (AccumT w m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
(Monoid w, MonadReader r m) => MonadReader r (WriterT w m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
(Monoid w, MonadReader r m) => MonadReader r (WriterT w m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
(Monoid w, MonadReader r m) => MonadReader r (WriterT w m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
MonadReader r ((->) r)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
MonadReader r' m => MonadReader r' (ContT r m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
(Comonad w, MonadReader e m) => MonadReader e (CoT w m)Defined in kan-extensions-5.2.7 · Control.Monad.Co
(m ~~ m', MonadReader r m') => MonadReader r (Codensity m)Defined in kan-extensions-5.2.7 · Control.Monad.Codensity
(Monad m, Monoid w) => MonadReader r (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
(Monad m, Monoid w) => MonadReader r (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class
(Monad m, Monoid w) => MonadReader r (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.Reader.Class

classclass Monad m => MonadState s (m :: Type -> Type) | m -> s where

Minimal definition is either both of get and put or just state

Methods

get :: m s
Return the state from the internals of the monad.
put :: s -> m ()
Replace the state inside the monad.
state :: (s -> (a, s)) -> m a
Embed a simple state action into the monad.

Instances26MonadState, …

MonadState s m => MonadState s (CatchT m)Defined in exceptions-0.10.9 · Control.Monad.Catch.Pure
MonadState s m => MonadState s (Free m)Defined in free-5.2 · Control.Monad.Free
MonadState s m => MonadState s (Free m)Defined in free-5.2 · Control.Monad.Free.Ap
MonadState s m => MonadState s (F m)Defined in free-5.2 · Control.Monad.Free.Church
MonadState s m => MonadState s (IterT m)Defined in free-5.2 · Control.Monad.Trans.Iter
MonadState s m => MonadState s (MaybeT m)Defined in mtl-2.3.1 · Control.Monad.State.Class
Monad m => MonadState s (StateT s m)Defined in mtl-2.3.1 · Control.Monad.State.Class
Monad m => MonadState s (StateT s m)Defined in mtl-2.3.1 · Control.Monad.State.Class
MonadState s m => MonadState s (FT f m)Defined in free-5.2 · Control.Monad.Trans.Free.Church
MonadState s m => MonadState s (ExceptT e m)Defined in mtl-2.3.1 · Control.Monad.State.Class
MonadState s m => MonadState s (IdentityT m)Defined in mtl-2.3.1 · Control.Monad.State.Class
MonadState s m => MonadState s (ReaderT r m)Defined in mtl-2.3.1 · Control.Monad.State.Class
MonadState s m => MonadState s (SelectT r m)Defined in mtl-2.3.1 · Control.Monad.State.Class
(Representable g, Monad m, Rep g ~ s) => MonadState s (StateT g m)Defined in adjunctions-4.4.3 · Control.Monad.Representable.State
(Applicative f, MonadState s m) => MonadState s (FreeT f m)Defined in free-5.2 · Control.Monad.Trans.Free.Ap
(Functor f, MonadState s m) => MonadState s (FreeT f m)Defined in free-5.2 · Control.Monad.Trans.Free
(Monoid w, MonadState s m) => MonadState s (AccumT w m)Defined in mtl-2.3.1 · Control.Monad.State.Class
(Monoid w, MonadState s m) => MonadState s (WriterT w m)Defined in mtl-2.3.1 · Control.Monad.State.Class
(Monoid w, MonadState s m) => MonadState s (WriterT w m)Defined in mtl-2.3.1 · Control.Monad.State.Class
(Monoid w, MonadState s m) => MonadState s (WriterT w m)Defined in mtl-2.3.1 · Control.Monad.State.Class
MonadState s m => MonadState s (ContT r m)Defined in mtl-2.3.1 · Control.Monad.State.Class
(Comonad w, MonadState s m) => MonadState s (CoT w m)Defined in kan-extensions-5.2.7 · Control.Monad.Co
(m ~~ m', MonadReader r m') => MonadState r (Codensity m)Defined in kan-extensions-5.2.7 · Control.Monad.Codensity
(Monad m, Monoid w) => MonadState s (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.State.Class
(Monad m, Monoid w) => MonadState s (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.State.Class
(Monad m, Monoid w) => MonadState s (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.State.Class

classclass (Monoid w, Monad m) => MonadWriter w (m :: Type -> Type) | m -> w where

Methods

writer :: (a, w) -> m a
writer (a,w) embeds a simple writer action.
tell :: w -> m ()
tell w is an action that produces the output w.
listen :: m a -> m (a, w)
listen m is an action that executes the action m and adds its output to the value of the computation.
pass :: m (a, w -> w) -> m a
pass m is an action that executes the action m, which returns a value and a function, and returns the value, applying the function to the output.

Instances25MonadWriter, …

Monoid w => MonadWriter w (Tuple2 w)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
MonadWriter e m => MonadWriter e (Free m)Defined in free-5.2 · Control.Monad.Free
MonadWriter e m => MonadWriter e (Free m)Defined in free-5.2 · Control.Monad.Free.Ap
MonadWriter w m => MonadWriter w (CatchT m)Defined in exceptions-0.10.9 · Control.Monad.Catch.Pure
MonadWriter w m => MonadWriter w (F m)Defined in free-5.2 · Control.Monad.Free.Church
MonadWriter w m => MonadWriter w (IterT m)Defined in free-5.2 · Control.Monad.Trans.Iter
MonadWriter w m => MonadWriter w (MaybeT m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
MonadWriter w m => MonadWriter w (ExceptT e m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
MonadWriter w m => MonadWriter w (IdentityT m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
MonadWriter w m => MonadWriter w (ReaderT r m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
MonadWriter w m => MonadWriter w (StateT s m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
MonadWriter w m => MonadWriter w (StateT s m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
(Representable f, MonadWriter w m) => MonadWriter w (ReaderT f m)Defined in adjunctions-4.4.3 · Control.Monad.Representable.Reader
(Representable g, MonadWriter w m) => MonadWriter w (StateT g m)Defined in adjunctions-4.4.3 · Control.Monad.Representable.State
(Applicative f, MonadWriter w m) => MonadWriter w (FreeT f m)Defined in free-5.2 · Control.Monad.Trans.Free.Ap
(Functor f, MonadWriter w m) => MonadWriter w (FreeT f m)Defined in free-5.2 · Control.Monad.Trans.Free
(Functor f, MonadWriter w m) => MonadWriter w (FT f m)Defined in free-5.2 · Control.Monad.Trans.Free.Church
(Monoid w, Monad m) => MonadWriter w (WriterT w m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
(Monoid w, Monad m) => MonadWriter w (WriterT w m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
(Monoid w, Monad m) => MonadWriter w (WriterT w m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
(Monoid w', MonadWriter w m) => MonadWriter w (AccumT w' m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
There are two valid instances for AccumT. It could either:
1. Lift the operations to the inner MonadWriter
2. Handle the operations itself, à la a WriterT.
This instance chooses (1), reflecting that the intent of AccumT as a type is different than that of WriterT.
(Comonad w, MonadWriter e m) => MonadWriter e (CoT w m)Defined in kan-extensions-5.2.7 · Control.Monad.Co
(Monoid w, Monad m) => MonadWriter w (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
(Monoid w, Monad m) => MonadWriter w (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class
(Monoid w, Monad m) => MonadWriter w (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.Writer.Class

class

class (Monoid w, MonadReader r m, MonadWriter w m, MonadState s m) => MonadRWS r w s (m :: Type -> Type) | m -> r, m -> w, m -> s

Instances7MonadRWS, …

MonadRWS r w s m => MonadRWS r w s (CatchT m)Defined in exceptions-0.10.9 · Control.Monad.Catch.Pure
MonadRWS r w s m => MonadRWS r w s (MaybeT m)Defined in mtl-2.3.1 · Control.Monad.RWS.Class
MonadRWS r w s m => MonadRWS r w s (ExceptT e m)Defined in mtl-2.3.1 · Control.Monad.RWS.Class
MonadRWS r w s m => MonadRWS r w s (IdentityT m)Defined in mtl-2.3.1 · Control.Monad.RWS.Class
(Monoid w, Monad m) => MonadRWS r w s (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.RWS.Class
(Monoid w, Monad m) => MonadRWS r w s (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.RWS.Class
(Monoid w, Monad m) => MonadRWS r w s (RWST r w s m)Defined in mtl-2.3.1 · Control.Monad.RWS.Class