rio-0.1.22.0: A standard library for Haskell
Safe HaskellSafe-Inferred
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 Source #

Minimal complete definition

(writer | tell), listen, pass

Methods

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

writer (a,w) embeds a simple writer action.

tell :: w -> m () Source #

tell w is an action that produces the output w.

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

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 Source #

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

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

Defined in RIO.Prelude.RIO

Methods

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

tell :: w -> RIO env () Source #

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

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

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

Defined in Control.Monad.Writer.Class

Methods

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

tell :: w -> MaybeT m () Source #

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

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

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

Since: mtl-2.2.2

Instance details

Defined in Control.Monad.Writer.Class

Methods

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

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

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

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

(Monoid w', MonadWriter w m) => MonadWriter w (AccumT w' m)

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.

Since: mtl-2.3

Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> AccumT w' m a Source #

tell :: w -> AccumT w' m () Source #

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

pass :: AccumT w' m (a, w -> w) -> AccumT w' m a Source #

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 Source #

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

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

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

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

Defined in Control.Monad.Writer.Class

Methods

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

tell :: w -> IdentityT m () Source #

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

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

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

Defined in Control.Monad.Writer.Class

Methods

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

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

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

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

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

Defined in Control.Monad.Writer.Class

Methods

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

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

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

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

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

Defined in Control.Monad.Writer.Class

Methods

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

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

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

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

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

Since: mtl-2.3

Instance details

Defined in Control.Monad.Writer.Class

Methods

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

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

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

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

(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 Source #

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

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

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

(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 Source #

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

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

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

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

Since: mtl-2.3

Instance details

Defined in Control.Monad.Writer.Class

Methods

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

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

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

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

(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 Source #

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

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

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

(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 Source #

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

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

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

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

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 Source #

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 Source #

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) Source #

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

execWriter :: Writer w a -> w Source #

Extract the output from a writer computation.

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

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

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

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

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

Defined in Control.Monad.Reader.Class

Methods

ask :: WriterT w m r Source #

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

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

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

Defined in Control.Monad.State.Class

Methods

get :: WriterT w m s Source #

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

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

(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 Source #

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

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

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

Monoid w => MonadTrans (WriterT w) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

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

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

Defined in Control.Monad.Trans.Writer.Lazy

Methods

fail :: String -> WriterT w m a Source #

(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 Source #

(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 Source #

(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) Source #

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

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

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

Defined in Control.Monad.Trans.Writer.Lazy

Methods

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

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

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

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

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

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

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

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

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

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

null :: WriterT w f a -> Bool Source #

length :: WriterT w f a -> Int Source #

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

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

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

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

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

(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 Source #

(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 Source #

(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) Source #

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

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

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

(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 Source #

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

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

Defined in Control.Monad.Trans.Writer.Lazy

Methods

contramap :: (a' -> a) -> WriterT w m a -> WriterT w m a' Source #

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

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) Source #

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

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

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

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

Defined in Control.Monad.Trans.Writer.Lazy

Methods

empty :: WriterT w m a Source #

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

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

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

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

Defined in Control.Monad.Trans.Writer.Lazy

Methods

pure :: a -> WriterT w m a Source #

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

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

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

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

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 Source #

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

(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 Source #

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

return :: a -> WriterT w m a Source #

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

Defined in Control.Monad.Trans.Writer.Lazy

Methods

mzero :: WriterT w m a Source #

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

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

Defined in Control.Monad.Catch

Methods

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

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

Defined in Control.Monad.Catch

Methods

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

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

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

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

Defined in Control.Monad.Catch

Methods

throwM :: (HasCallStack, Exception e) => e -> WriterT w m a Source #

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

Defined in Control.Monad.Primitive

Associated Types

type PrimState (WriterT w m) Source #

Methods

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

(Monoid w, Zoom m n s t) => Zoom (WriterT w m) (WriterT w n) s t 
Instance details

Defined in Lens.Micro.Mtl.Internal

Methods

zoom :: LensLike' (Zoomed (WriterT w m) c) t s -> WriterT w m c -> WriterT w n c Source #

Generic (WriterT w m a) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Associated Types

type Rep (WriterT w m a) :: Type -> Type Source #

Methods

from :: WriterT w m a -> Rep (WriterT w m a) x Source #

to :: Rep (WriterT w m a) x -> WriterT w m a Source #

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

Defined in Control.Monad.Trans.Writer.Lazy

(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 Source #

show :: WriterT w m a -> String Source #

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

(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 Source #

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

(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 Source #

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

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

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

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

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

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

type Zoomed (WriterT w m) 
Instance details

Defined in Lens.Micro.Mtl.Internal

type Zoomed (WriterT w m) = FocusingPlus w (Zoomed m)
type PrimState (WriterT w m) 
Instance details

Defined in Control.Monad.Primitive

type PrimState (WriterT w m) = PrimState m
type Rep (WriterT w m a) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

type Rep (WriterT w m a) = D1 ('MetaData "WriterT" "Control.Monad.Trans.Writer.Lazy" "transformers-0.6.1.0" 'True) (C1 ('MetaCons "WriterT" 'PrefixI 'True) (S1 ('MetaSel ('Just "runWriterT") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (m (a, w)))))

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

Extract the output from a writer computation.

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

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