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Language	GHC2021

Control.Monad.Ology.Specific.WriterT

Contents

Orphan instances

Synopsis

tell :: forall (m :: Type -> Type) w. Monad m => w -> WriterT w m ()
listen :: forall (m :: Type -> Type) w a. Monad m => WriterT w m a -> WriterT w m (a, w)
listens :: forall (m :: Type -> Type) w b a. Monad m => (w -> b) -> WriterT w m a -> WriterT w m (a, b)
censor :: forall (m :: Type -> Type) w a. Monad m => (w -> w) -> WriterT w m a -> WriterT w m a
newtype WriterT w (m :: Type -> Type) a = WriterT {
- runWriterT :: m (a, w)
}
type Writer w = WriterT w Identity
runWriter :: Writer w a -> (a, w)
execWriter :: Writer w a -> w
mapWriter :: ((a, w) -> (b, w')) -> Writer w a -> Writer w' b
execWriterT :: Monad m => WriterT w m a -> m w
mapWriterT :: (m (a, w) -> n (b, w')) -> WriterT w m a -> WriterT w' n b
writer :: forall (m :: Type -> Type) a w. Monad m => (a, w) -> WriterT w m a
pass :: forall (m :: Type -> Type) w a. Monad m => WriterT w m (a, w -> w) -> WriterT w m a
collect :: forall (m :: Type -> Type) w a. (Monad m, Monoid w) => WriterT w m a -> WriterT w m (a, w)
evalWriterT :: Monad m => WriterT w m a -> m a

Documentation

tell :: forall (m :: Type -> Type) w. Monad m => w -> WriterT w m () #

tell w is an action that produces the output w.

listen :: forall (m :: Type -> Type) w a. Monad m => WriterT w m a -> WriterT w m (a, w) #

listen m is an action that executes the action m and adds its output to the value of the computation.

runWriterT (listen m) = liftM (\ (a, w) -> ((a, w), w)) (runWriterT m)

listens :: forall (m :: Type -> Type) w b a. Monad m => (w -> b) -> WriterT w m a -> WriterT w 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)

runWriterT (listens f m) = liftM (\ (a, w) -> ((a, f w), w)) (runWriterT m)

censor :: forall (m :: Type -> Type) w a. Monad m => (w -> w) -> WriterT w m a -> WriterT w 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)

runWriterT (censor f m) = liftM (\ (a, w) -> (a, f w)) (runWriterT m)

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 runWriterT :: m (a, w)

Instances

Instances details

(Read w, Read1 m) => Lifting Read (WriterT w m :: Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: Read a :- Read (WriterT w m a) #

(Show w, Show1 m) => Lifting Show (WriterT w m :: Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: Show a :- Show (WriterT w m a) #

(Eq w, Eq1 m) => Lifting Eq (WriterT w m :: Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: Eq a :- Eq (WriterT w m a) #

(Ord w, Ord1 m) => Lifting Ord (WriterT w m :: Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: Ord a :- Ord (WriterT w m a) #

Monoid w => TransConstraint MonadFail (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadFail m => Dict (MonadFail (WriterT w m)) Source #

Monoid w => TransConstraint MonadFix (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadFix m => Dict (MonadFix (WriterT w m)) Source #

Monoid w => TransConstraint MonadIO (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadIO m => Dict (MonadIO (WriterT w m)) Source #

Monoid w => TransConstraint Applicative (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). Applicative m => Dict (Applicative (WriterT w m)) Source #

TransConstraint Functor (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). Functor m => Dict (Functor (WriterT w m)) Source #

Monoid w => TransConstraint Monad (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). Monad m => Dict (Monad (WriterT w m)) Source #

Monoid w => TransConstraint MonadPlus (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadPlus m => Dict (MonadPlus (WriterT w m)) Source #

Monoid w => TransConstraint MonadException (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadException m => Dict (MonadException (WriterT w m)) Source #

Monoid w => TransConstraint MonadExtract (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadExtract m => Dict (MonadExtract (WriterT w m)) Source #

Monoid w => TransConstraint MonadInner (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadInner m => Dict (MonadInner (WriterT w m)) Source #

(MonadCatch e m, Monoid w) => MonadCatch e (WriterT w m) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

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

(MonadThrow e m, Monoid w) => MonadThrow e (WriterT w m) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

throw :: e -> WriterT w m a Source #

Monoid w => MonadTransCoerce (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

transCoerce :: forall (m1 :: Type -> Type) (m2 :: Type -> Type). Coercible m1 m2 => Dict (Coercible (WriterT w m1) (WriterT w m2)) Source #

Monoid w => MonadTransHoist (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hoist :: forall (m1 :: Type -> Type) (m2 :: Type -> Type). (Monad m1, Monad m2) => (m1 --> m2) -> WriterT w m1 --> WriterT w m2 Source #

Monoid w => MonadTransTunnel (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Associated Types

type Tunnel (WriterT w)
Instance details Defined in Control.Monad.Ology.Specific.WriterT type Tunnel (WriterT w) = (,) w

Methods

tunnel :: Monad m => ((forall (m1 :: Type -> Type) a. Monad m1 => WriterT w m1 a -> m1 (Tunnel (WriterT w) a)) -> m (Tunnel (WriterT w) r)) -> WriterT w m r Source #

Monoid w => MonadTransUnlift (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

liftWithUnlift :: MonadIO m => (Unlift MonadTunnelIO (WriterT w) -> m r) -> WriterT w m r Source #

getDiscardingUnlift :: forall (m :: Type -> Type). Monad m => WriterT w m (WUnlift MonadTunnelIO (WriterT w)) 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 #

Monoid w => TransConstraint (MonadCatch e) (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadCatch e m => Dict (MonadCatch e (WriterT w m)) Source #

Monoid w => TransConstraint (MonadThrow e) (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadThrow e m => Dict (MonadThrow e (WriterT w m)) 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 #

(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, 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) #

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 #

(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 #

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, 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 #

Invariant m => Invariant (WriterT w m)

from the transformers package

Instance details

Defined in Data.Functor.Invariant

Methods

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

(Monoid w, MonadException m) => MonadException (WriterT w m) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Associated Types

type Exc (WriterT w m)
Instance details Defined in Control.Monad.Ology.Specific.WriterT type Exc (WriterT w m) = Exc m

Methods

throwExc :: Exc (WriterT w m) -> WriterT w m a Source #

catchExc :: WriterT w m a -> (Exc (WriterT w m) -> WriterT w m a) -> WriterT w m a Source #

(MonadExtract m, Monoid w) => MonadExtract (WriterT w m) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

mToValue :: Extract (WriterT w m) Source #

(MonadInner m, Monoid w) => MonadInner (WriterT w m) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

Methods

retrieveInner :: WriterT w m a -> Result (Exc (WriterT w m)) a Source #

Monoid w => Lifting MonadFix (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). MonadFix a :- MonadFix (WriterT w a) #

Monoid w => Lifting MonadIO (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). MonadIO a :- MonadIO (WriterT w a) #

Lifting Foldable (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Foldable a :- Foldable (WriterT w a) #

Eq w => Lifting Eq1 (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Eq1 a :- Eq1 (WriterT w a) #

Ord w => Lifting Ord1 (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Ord1 a :- Ord1 (WriterT w a) #

Read w => Lifting Read1 (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Read1 a :- Read1 (WriterT w a) #

Show w => Lifting Show1 (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Show1 a :- Show1 (WriterT w a) #

Lifting Traversable (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Traversable a :- Traversable (WriterT w a) #

Monoid w => Lifting Alternative (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Alternative a :- Alternative (WriterT w a) #

Monoid w => Lifting Applicative (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Applicative a :- Applicative (WriterT w a) #

Lifting Functor (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Functor a :- Functor (WriterT w a) #

Monoid w => Lifting Monad (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). Monad a :- Monad (WriterT w a) #

Monoid w => Lifting MonadPlus (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). MonadPlus a :- MonadPlus (WriterT w a) #

Monoid w => Lifting MonadCont (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). MonadCont a :- MonadCont (WriterT w a) #

Monoid w => Lifting (MonadError e :: (Type -> Type) -> Constraint) (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). MonadError e a :- MonadError e (WriterT w a) #

Monoid w => Lifting (MonadReader r :: (Type -> Type) -> Constraint) (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). MonadReader r a :- MonadReader r (WriterT w a) #

Monoid w => Lifting (MonadState s :: (Type -> Type) -> Constraint) (WriterT w :: (Type -> Type) -> Type -> Type)

Instance details

Defined in Data.Constraint.Lifting

Methods

lifting :: forall (a :: Type -> Type). MonadState s a :- MonadState s (WriterT w a) #

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-0.6.1.0-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 Tunnel (WriterT w) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

type Tunnel (WriterT w) = (,) w

type Exc (WriterT w m) Source #

Instance details

Defined in Control.Monad.Ology.Specific.WriterT

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

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.

```
execWriter m = snd (runWriter m)
```

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.

runWriter (mapWriter f m) = f (runWriter m)

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

Extract the output from a writer computation.

execWriterT m = liftM snd (runWriterT m)

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.

runWriterT (mapWriterT f m) = f (runWriterT m)

writer :: forall (m :: Type -> Type) a w. Monad m => (a, w) -> WriterT w m a #

Construct a writer computation from a (result, output) pair. (The inverse of runWriter.)

pass :: forall (m :: Type -> Type) w a. Monad m => WriterT w m (a, w -> w) -> WriterT 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.

runWriterT (pass m) = liftM (\ ((a, f), w) -> (a, f w)) (runWriterT m)

collect :: forall (m :: Type -> Type) w a. (Monad m, Monoid w) => WriterT w m a -> WriterT w m (a, w) Source #

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

Orphan instances

Monoid w => TransConstraint MonadFail (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadFail m => Dict (MonadFail (WriterT w m)) Source #

Monoid w => TransConstraint MonadFix (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadFix m => Dict (MonadFix (WriterT w m)) Source #

Monoid w => TransConstraint MonadIO (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadIO m => Dict (MonadIO (WriterT w m)) Source #

Monoid w => TransConstraint Applicative (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). Applicative m => Dict (Applicative (WriterT w m)) Source #

TransConstraint Functor (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). Functor m => Dict (Functor (WriterT w m)) Source #

Monoid w => TransConstraint Monad (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). Monad m => Dict (Monad (WriterT w m)) Source #

Monoid w => TransConstraint MonadPlus (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadPlus m => Dict (MonadPlus (WriterT w m)) Source #

Monoid w => TransConstraint MonadException (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadException m => Dict (MonadException (WriterT w m)) Source #

Monoid w => TransConstraint MonadExtract (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadExtract m => Dict (MonadExtract (WriterT w m)) Source #

Monoid w => TransConstraint MonadInner (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadInner m => Dict (MonadInner (WriterT w m)) Source #

(MonadCatch e m, Monoid w) => MonadCatch e (WriterT w m) Source #

Instance details

Methods

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

(MonadThrow e m, Monoid w) => MonadThrow e (WriterT w m) Source #

Instance details

Methods

throw :: e -> WriterT w m a Source #

Monoid w => MonadTransCoerce (WriterT w) Source #

Instance details

Methods

transCoerce :: forall (m1 :: Type -> Type) (m2 :: Type -> Type). Coercible m1 m2 => Dict (Coercible (WriterT w m1) (WriterT w m2)) Source #

Monoid w => MonadTransHoist (WriterT w) Source #

Instance details

Methods

hoist :: forall (m1 :: Type -> Type) (m2 :: Type -> Type). (Monad m1, Monad m2) => (m1 --> m2) -> WriterT w m1 --> WriterT w m2 Source #

Monoid w => MonadTransTunnel (WriterT w) Source #

Instance details

Associated Types

type Tunnel (WriterT w)
Instance details Defined in Control.Monad.Ology.Specific.WriterT type Tunnel (WriterT w) = (,) w

Methods

tunnel :: Monad m => ((forall (m1 :: Type -> Type) a. Monad m1 => WriterT w m1 a -> m1 (Tunnel (WriterT w) a)) -> m (Tunnel (WriterT w) r)) -> WriterT w m r Source #

Monoid w => MonadTransUnlift (WriterT w) Source #

Instance details

Methods

liftWithUnlift :: MonadIO m => (Unlift MonadTunnelIO (WriterT w) -> m r) -> WriterT w m r Source #

getDiscardingUnlift :: forall (m :: Type -> Type). Monad m => WriterT w m (WUnlift MonadTunnelIO (WriterT w)) Source #

Monoid w => TransConstraint (MonadCatch e) (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadCatch e m => Dict (MonadCatch e (WriterT w m)) Source #

Monoid w => TransConstraint (MonadThrow e) (WriterT w) Source #

Instance details

Methods

hasTransConstraint :: forall (m :: Type -> Type). MonadThrow e m => Dict (MonadThrow e (WriterT w m)) Source #

(Monoid w, MonadException m) => MonadException (WriterT w m) Source #

Instance details

Associated Types

type Exc (WriterT w m)
Instance details Defined in Control.Monad.Ology.Specific.WriterT type Exc (WriterT w m) = Exc m

Methods

throwExc :: Exc (WriterT w m) -> WriterT w m a Source #

catchExc :: WriterT w m a -> (Exc (WriterT w m) -> WriterT w m a) -> WriterT w m a Source #

(MonadExtract m, Monoid w) => MonadExtract (WriterT w m) Source #

Instance details

Methods

mToValue :: Extract (WriterT w m) Source #

(MonadInner m, Monoid w) => MonadInner (WriterT w m) Source #

Instance details

Methods

retrieveInner :: WriterT w m a -> Result (Exc (WriterT w m)) a Source #