rio-0.1.15.1: A standard library for Haskell

Safe HaskellSafe
LanguageHaskell2010

RIO.Writer

Description

Provides reexports of MonadWriter and related helpers.

Since: 0.1.4.0

Synopsis

Documentation

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

Minimal complete definition

(writer | tell), listen, pass

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.

Instances
(Monoid w, HasWriteRef w env) => MonadWriter w (RIO env) Source # 
Instance details

Defined in RIO.Prelude.RIO

Methods

writer :: (a, w) -> RIO env a #

tell :: w -> RIO env () #

listen :: RIO env a -> RIO env (a, w) #

pass :: RIO env (a, w -> w) -> RIO env a #

MonadWriter w m => MonadWriter w (MaybeT m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> MaybeT m a #

tell :: w -> MaybeT m () #

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

pass :: MaybeT m (a, w -> w) -> MaybeT m a #

Monoid w => MonadWriter w ((,) w)

NOTE: This instance is only defined for base >= 4.9.0.

Since: mtl-2.2.2

Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> (w, a) #

tell :: w -> (w, ()) #

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

pass :: (w, (a, w -> w)) -> (w, a) #

(Monoid w, Monad m) => MonadWriter w (WriterT w m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> WriterT w m a #

tell :: w -> WriterT w m () #

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

pass :: WriterT w m (a, w -> w) -> WriterT w m a #

(Monoid w, Monad m) => MonadWriter w (WriterT w m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> WriterT w m a #

tell :: w -> WriterT w m () #

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

pass :: WriterT w m (a, w -> w) -> WriterT w m a #

MonadWriter w m => MonadWriter w (StateT s m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> StateT s m a #

tell :: w -> StateT s m () #

listen :: StateT s m a -> StateT s m (a, w) #

pass :: StateT s m (a, w -> w) -> StateT s m a #

MonadWriter w m => MonadWriter w (StateT s m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> StateT s m a #

tell :: w -> StateT s m () #

listen :: StateT s m a -> StateT s m (a, w) #

pass :: StateT s m (a, w -> w) -> StateT s m a #

MonadWriter w m => MonadWriter w (IdentityT m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> IdentityT m a #

tell :: w -> IdentityT m () #

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

pass :: IdentityT m (a, w -> w) -> IdentityT m a #

MonadWriter w m => MonadWriter w (ExceptT e m)

Since: mtl-2.2

Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> ExceptT e m a #

tell :: w -> ExceptT e m () #

listen :: ExceptT e m a -> ExceptT e m (a, w) #

pass :: ExceptT e m (a, w -> w) -> ExceptT e m a #

(Error e, MonadWriter w m) => MonadWriter w (ErrorT e m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> ErrorT e m a #

tell :: w -> ErrorT e m () #

listen :: ErrorT e m a -> ErrorT e m (a, w) #

pass :: ErrorT e m (a, w -> w) -> ErrorT e m a #

MonadWriter w m => MonadWriter w (ReaderT r m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> ReaderT r m a #

tell :: w -> ReaderT r m () #

listen :: ReaderT r m a -> ReaderT r m (a, w) #

pass :: ReaderT r m (a, w -> w) -> ReaderT r m a #

(Monoid w, Monad m) => MonadWriter w (RWST r w s m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> RWST r w s m a #

tell :: w -> RWST r w s m () #

listen :: RWST r w s m a -> RWST r w s m (a, w) #

pass :: RWST r w s m (a, w -> w) -> RWST r w s m a #

(Monoid w, Monad m) => MonadWriter w (RWST r w s m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> RWST r w s m a #

tell :: w -> RWST r w s m () #

listen :: RWST r w s m a -> RWST r w s m (a, w) #

pass :: RWST r w s m (a, w -> w) -> RWST r w s m a #

listens :: 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.

censor :: 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.

type Writer w = WriterT w Identity #

A writer monad parameterized by the type w of output to accumulate.

The return function produces the output mempty, while >>= combines the outputs of the subcomputations using mappend.

runWriter :: Writer w a -> (a, w) #

Unwrap a writer computation as a (result, output) pair. (The inverse of writer.)

execWriter :: Writer w a -> w #

Extract the output from a writer computation.

mapWriter :: ((a, w) -> (b, w')) -> Writer w a -> Writer w' b #

Map both the return value and output of a computation using the given function.

newtype WriterT w (m :: Type -> Type) a #

A writer monad parameterized by:

  • w - the output to accumulate.
  • m - The inner monad.

The return function produces the output mempty, while >>= combines the outputs of the subcomputations using mappend.

Constructors

WriterT 

Fields

Instances
(Monoid w, Monad m) => MonadWriter w (WriterT w m) 
Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> WriterT w m a #

tell :: w -> WriterT w m () #

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

pass :: WriterT w m (a, w -> w) -> WriterT w m a #

(Monoid w, MonadState s m) => MonadState s (WriterT w m) 
Instance details

Defined in Control.Monad.State.Class

Methods

get :: WriterT w m s #

put :: s -> WriterT w m () #

state :: (s -> (a, s)) -> WriterT w m a #

(Monoid w, MonadReader r m) => MonadReader r (WriterT w m) 
Instance details

Defined in Control.Monad.Reader.Class

Methods

ask :: WriterT w m r #

local :: (r -> r) -> WriterT w m a -> WriterT w m a #

reader :: (r -> a) -> WriterT w m a #

Monoid w => MonadTrans (WriterT w) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

lift :: Monad m => m a -> WriterT w m a #

(Monoid w, Monad m) => Monad (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

(>>=) :: WriterT w m a -> (a -> WriterT w m b) -> WriterT w m b #

(>>) :: WriterT w m a -> WriterT w m b -> WriterT w m b #

return :: a -> WriterT w m a #

fail :: String -> WriterT w m a #

Functor m => Functor (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

fmap :: (a -> b) -> WriterT w m a -> WriterT w m b #

(<$) :: a -> WriterT w m b -> WriterT w m a #

(Monoid w, MonadFix m) => MonadFix (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

mfix :: (a -> WriterT w m a) -> WriterT w m a #

(Monoid w, MonadFail m) => MonadFail (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

fail :: String -> WriterT w m a #

(Monoid w, Applicative m) => Applicative (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

pure :: a -> WriterT w m a #

(<*>) :: WriterT w m (a -> b) -> WriterT w m a -> WriterT w m b #

liftA2 :: (a -> b -> c) -> WriterT w m a -> WriterT w m b -> WriterT w m c #

(*>) :: WriterT w m a -> WriterT w m b -> WriterT w m b #

(<*) :: WriterT w m a -> WriterT w m b -> WriterT w m a #

Foldable f => Foldable (WriterT w f) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

fold :: Monoid m => WriterT w f m -> m #

foldMap :: Monoid m => (a -> m) -> WriterT w f a -> m #

foldr :: (a -> b -> b) -> b -> WriterT w f a -> b #

foldr' :: (a -> b -> b) -> b -> WriterT w f a -> b #

foldl :: (b -> a -> b) -> b -> WriterT w f a -> b #

foldl' :: (b -> a -> b) -> b -> WriterT w f a -> b #

foldr1 :: (a -> a -> a) -> WriterT w f a -> a #

foldl1 :: (a -> a -> a) -> WriterT w f a -> a #

toList :: WriterT w f a -> [a] #

null :: WriterT w f a -> Bool #

length :: WriterT w f a -> Int #

elem :: Eq a => a -> WriterT w f a -> Bool #

maximum :: Ord a => WriterT w f a -> a #

minimum :: Ord a => WriterT w f a -> a #

sum :: Num a => WriterT w f a -> a #

product :: Num a => WriterT w f a -> a #

Traversable f => Traversable (WriterT w f) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

traverse :: Applicative f0 => (a -> f0 b) -> WriterT w f a -> f0 (WriterT w f b) #

sequenceA :: Applicative f0 => WriterT w f (f0 a) -> f0 (WriterT w f a) #

mapM :: Monad m => (a -> m b) -> WriterT w f a -> m (WriterT w f b) #

sequence :: Monad m => WriterT w f (m a) -> m (WriterT w f a) #

Contravariant m => Contravariant (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

contramap :: (a -> b) -> WriterT w m b -> WriterT w m a #

(>$) :: b -> WriterT w m b -> WriterT w m a #

(Eq w, Eq1 m) => Eq1 (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

liftEq :: (a -> b -> Bool) -> WriterT w m a -> WriterT w m b -> Bool #

(Ord w, Ord1 m) => Ord1 (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

liftCompare :: (a -> b -> Ordering) -> WriterT w m a -> WriterT w m b -> Ordering #

(Read w, Read1 m) => Read1 (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (WriterT w m a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [WriterT w m a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (WriterT w m a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [WriterT w m a] #

(Show w, Show1 m) => Show1 (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> WriterT w m a -> ShowS #

liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [WriterT w m a] -> ShowS #

(Monoid w, MonadZip m) => MonadZip (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

mzip :: WriterT w m a -> WriterT w m b -> WriterT w m (a, b) #

mzipWith :: (a -> b -> c) -> WriterT w m a -> WriterT w m b -> WriterT w m c #

munzip :: WriterT w m (a, b) -> (WriterT w m a, WriterT w m b) #

(Monoid w, MonadIO m) => MonadIO (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

liftIO :: IO a -> WriterT w m a #

(Monoid w, Alternative m) => Alternative (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

empty :: WriterT w m a #

(<|>) :: WriterT w m a -> WriterT w m a -> WriterT w m a #

some :: WriterT w m a -> WriterT w m [a] #

many :: WriterT w m a -> WriterT w m [a] #

(Monoid w, MonadPlus m) => MonadPlus (WriterT w m) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

mzero :: WriterT w m a #

mplus :: WriterT w m a -> WriterT w m a -> WriterT w m a #

(MonadThrow m, Monoid w) => MonadThrow (WriterT w m) 
Instance details

Defined in Control.Monad.Catch

Methods

throwM :: Exception e => e -> WriterT w m a #

(MonadCatch m, Monoid w) => MonadCatch (WriterT w m) 
Instance details

Defined in Control.Monad.Catch

Methods

catch :: Exception e => WriterT w m a -> (e -> WriterT w m a) -> WriterT w m a #

(MonadMask m, Monoid w) => MonadMask (WriterT w m) 
Instance details

Defined in Control.Monad.Catch

Methods

mask :: ((forall a. WriterT w m a -> WriterT w m a) -> WriterT w m b) -> WriterT w m b #

uninterruptibleMask :: ((forall a. WriterT w m a -> WriterT w m a) -> WriterT w m b) -> WriterT w m b #

generalBracket :: WriterT w m a -> (a -> ExitCase b -> WriterT w m c) -> (a -> WriterT w m b) -> WriterT w m (b, c) #

(Monoid w, PrimMonad m) => PrimMonad (WriterT w m) 
Instance details

Defined in Control.Monad.Primitive

Associated Types

type PrimState (WriterT w m) :: Type #

Methods

primitive :: (State# (PrimState (WriterT w m)) -> (#State# (PrimState (WriterT w m)), a#)) -> WriterT w m a #

(Eq w, Eq1 m, Eq a) => Eq (WriterT w m a) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

(==) :: WriterT w m a -> WriterT w m a -> Bool #

(/=) :: WriterT w m a -> WriterT w m a -> Bool #

(Ord w, Ord1 m, Ord a) => Ord (WriterT w m a) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

compare :: WriterT w m a -> WriterT w m a -> Ordering #

(<) :: WriterT w m a -> WriterT w m a -> Bool #

(<=) :: WriterT w m a -> WriterT w m a -> Bool #

(>) :: WriterT w m a -> WriterT w m a -> Bool #

(>=) :: WriterT w m a -> WriterT w m a -> Bool #

max :: WriterT w m a -> WriterT w m a -> WriterT w m a #

min :: WriterT w m a -> WriterT w m a -> WriterT w m a #

(Read w, Read1 m, Read a) => Read (WriterT w m a) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

readsPrec :: Int -> ReadS (WriterT w m a) #

readList :: ReadS [WriterT w m a] #

readPrec :: ReadPrec (WriterT w m a) #

readListPrec :: ReadPrec [WriterT w m a] #

(Show w, Show1 m, Show a) => Show (WriterT w m a) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

showsPrec :: Int -> WriterT w m a -> ShowS #

show :: WriterT w m a -> String #

showList :: [WriterT w m a] -> ShowS #

type PrimState (WriterT w m) 
Instance details

Defined in Control.Monad.Primitive

type PrimState (WriterT w m) = PrimState m

execWriterT :: Monad m => WriterT w m a -> m w #

Extract the output from a writer computation.

mapWriterT :: (m (a, w) -> n (b, w')) -> WriterT w m a -> WriterT w' n b #

Map both the return value and output of a computation using the given function.