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 #

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

Instances details
MonadWriter w m => MonadWriter w (CatchT m) 
Instance details

Defined in Control.Monad.Catch.Pure

Methods

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

tell :: w -> CatchT m () #

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

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

(Monoid w, HasWriteRef w env) => MonadWriter w (RIO env) # 
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)

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', 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 #

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

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

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

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 (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 #

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 #

(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 #

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 #

(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 (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 #

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 #

(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 m >>= k combines the outputs of the subcomputations using mappend (also known as <>):

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 m >>= k combines the outputs of the subcomputations using mappend (also known as <>):

Constructors

WriterT 

Fields

Instances

Instances details
(MonadAccum w' m, Monoid w) => MonadAccum w' (WriterT w m)

Since: mtl-2.3

Instance details

Defined in Control.Monad.Accum

Methods

look :: WriterT w m w' #

add :: w' -> WriterT w m () #

accum :: (w' -> (a, w')) -> WriterT w m a #

(Monoid w, MonadError e m) => MonadError e (WriterT w m) 
Instance details

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> WriterT w m a #

catchError :: WriterT w m a -> (e -> WriterT w m a) -> 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 #

(MonadSelect w' m, Monoid w) => MonadSelect w' (WriterT w m)

'Readerizes' the writer: the 'ranking' function can see the value that's been accumulated (of type w), but can't add anything to the log. Effectively, can be thought of as 'extending' the 'ranking' by all values of w, but which w gets given to any rank calls is predetermined by the 'outer writer' (and cannot change).

Since: mtl-2.3

Instance details

Defined in Control.Monad.Select

Methods

select :: ((a -> w') -> a) -> 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, 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 => MonadTrans (WriterT w) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Methods

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

(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, 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) #

(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 #

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' #

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

(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 #

(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 #

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

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

(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 #

(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, 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 #

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, 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 #

(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 #

(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, 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 #

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 #

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) #

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

Defined in Control.Monad.Cont.Class

Methods

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

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

Defined in Control.Monad.Primitive

Associated Types

type PrimState (WriterT w m) 
Instance details

Defined in Control.Monad.Primitive

type PrimState (WriterT w m) = PrimState m

Methods

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

(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 #

Generic (WriterT w m a) 
Instance details

Defined in Control.Monad.Trans.Writer.Lazy

Associated Types

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-0.6.1.1-inplace" 'True) (C1 ('MetaCons "WriterT" 'PrefixI 'True) (S1 ('MetaSel ('Just "runWriterT") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (m (a, w)))))

Methods

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

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

(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 #

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-0.6.1.1-inplace" '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 #

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.