Safe Haskell	Safe-Inferred
Language	Haskell2010

Lens.Family2.State.Lazy

Contents

Compound Assignments
Strict Assignments
Types
Re-exports

Description

Lenses allow you to use fields of the state of a state monad as if they were variables in an imperative language. use is used to retrieve the value of a variable, and .= and %= allow you to set and modify a variable. C-style compound assignments are also provided.

Synopsis

zoom :: forall (m :: Type -> Type) c s a. Monad m => LensLike' (Zooming m c) s a -> StateT a m c -> StateT s m c
use :: MonadState s m => FoldLike a s t a b -> m a
uses :: MonadState s m => FoldLike r s t a b -> (a -> r) -> m r
(%=) :: MonadState s m => Setter s s a b -> (a -> b) -> m ()
assign :: MonadState s m => Setter s s a b -> b -> m ()
(.=) :: MonadState s m => Setter s s a b -> b -> m ()
(%%=) :: MonadState s m => LensLike (Writer c) s s a b -> (a -> (c, b)) -> m c
(<~) :: MonadState s m => Setter s s a b -> m b -> m ()
(+=) :: (MonadState s m, Num a) => Setter' s a -> a -> m ()
(-=) :: (MonadState s m, Num a) => Setter' s a -> a -> m ()
(*=) :: (MonadState s m, Num a) => Setter' s a -> a -> m ()
(//=) :: (MonadState s m, Fractional a) => Setter' s a -> a -> m ()
(&&=) :: MonadState s m => Setter' s Bool -> Bool -> m ()
(||=) :: MonadState s m => Setter' s Bool -> Bool -> m ()
(<>=) :: (MonadState s m, Monoid a) => Setter' s a -> a -> m ()
(%!=) :: MonadState s m => Setter s s a b -> (a -> b) -> m ()
(+!=) :: (MonadState s m, Num a) => Setter' s a -> a -> m ()
(-!=) :: (MonadState s m, Num a) => Setter' s a -> a -> m ()
(*!=) :: (MonadState s m, Num a) => Setter' s a -> a -> m ()
(//!=) :: (MonadState s m, Fractional a) => Setter' s a -> a -> m ()
(&&!=) :: MonadState s m => Setter' s Bool -> Bool -> m ()
(||!=) :: MonadState s m => Setter' s Bool -> Bool -> m ()
(<>!=) :: (MonadState s m, Monoid a) => Setter' s a -> a -> m ()
data Zooming (m :: Type -> Type) c a
type LensLike (f :: Type -> Type) s t a b = (a -> f b) -> s -> f t
type LensLike' (f :: Type -> Type) s a = (a -> f a) -> s -> f s
type FoldLike r s t a b = LensLike (Constant r :: Type -> Type) s t a b
data Constant a (b :: k)
type Setter s t a b = forall f. Identical f => LensLike f s t a b
type Setter' s a = forall f. Identical f => LensLike' f s a
class (Traversable f, Applicative f) => Identical (f :: Type -> Type)
data StateT s (m :: Type -> Type) a
class Monad m => MonadState s (m :: Type -> Type) | m -> s
type Writer w = WriterT w Identity

Documentation

zoom :: forall (m :: Type -> Type) c s a. Monad m => LensLike' (Zooming m c) s a -> StateT a m c -> StateT s m c #

zoom :: Monad m => Lens' s a -> StateT a m c -> StateT s m c

Lift a stateful operation on a field to a stateful operation on the whole state. This is a good way to call a "subroutine" that only needs access to part of the state.

zoom :: (Monad m, Monoid c) => Traversal' s a -> StateT a m c -> StateT s m c

Run the "subroutine" on each element of the traversal in turn and mconcat all the results together.

zoom :: Monad m => Traversal' s a -> StateT a m () -> StateT s m ()

Run the "subroutine" on each element the traversal in turn.

use :: MonadState s m => FoldLike a s t a b -> m a Source #

use :: MonadState s m => Getter s t a b -> m a

Retrieve a field of the state

use :: (MonadState s m, Monoid a) => Fold s t a b -> m a

Retrieve a monoidal summary of all the referenced fields from the state

uses :: MonadState s m => FoldLike r s t a b -> (a -> r) -> m r Source #

uses :: (MonadState s m, Monoid r) => Fold s t a b -> (a -> r) -> m r

Retrieve all the referenced fields from the state and foldMap the results together with f :: a -> r.

uses :: MonadState s m => Getter s t a b -> (a -> r) -> m r

Retrieve a field of the state and pass it through the function f :: a -> r.

uses l f = f <$> use l

(%=) :: MonadState s m => Setter s s a b -> (a -> b) -> m () infix 4 Source #

Modify a field of the state.

assign :: MonadState s m => Setter s s a b -> b -> m () Source #

Set a field of the state.

(.=) :: MonadState s m => Setter s s a b -> b -> m () infix 4 Source #

Set a field of the state.

(%%=) :: MonadState s m => LensLike (Writer c) s s a b -> (a -> (c, b)) -> m c infix 4 Source #

(%%=) :: MonadState s m => Lens s s a b -> (a -> (c, b)) -> m c

Modify a field of the state while returning another value.

(%%=) :: (MonadState s m, Monoid c) => Traversal s s a b -> (a -> (c, b)) -> m c

Modify each field of the state and return the mconcat of the other values.

(<~) :: MonadState s m => Setter s s a b -> m b -> m () infixr 2 Source #

Set a field of the state using the result of executing a stateful command.

Compound Assignments

(+=) :: (MonadState s m, Num a) => Setter' s a -> a -> m () infixr 4 Source #

(-=) :: (MonadState s m, Num a) => Setter' s a -> a -> m () infixr 4 Source #

(*=) :: (MonadState s m, Num a) => Setter' s a -> a -> m () infixr 4 Source #

(//=) :: (MonadState s m, Fractional a) => Setter' s a -> a -> m () infixr 4 Source #

(&&=) :: MonadState s m => Setter' s Bool -> Bool -> m () infixr 4 Source #

(||=) :: MonadState s m => Setter' s Bool -> Bool -> m () infixr 4 Source #

(<>=) :: (MonadState s m, Monoid a) => Setter' s a -> a -> m () infixr 4 Source #

Monoidally append a value to all referenced fields of the state.

Strict Assignments

(%!=) :: MonadState s m => Setter s s a b -> (a -> b) -> m () infix 4 Source #

Strictly modify a field of the state.

(+!=) :: (MonadState s m, Num a) => Setter' s a -> a -> m () infixr 4 Source #

(-!=) :: (MonadState s m, Num a) => Setter' s a -> a -> m () infixr 4 Source #

(*!=) :: (MonadState s m, Num a) => Setter' s a -> a -> m () infixr 4 Source #

(//!=) :: (MonadState s m, Fractional a) => Setter' s a -> a -> m () infixr 4 Source #

(&&!=) :: MonadState s m => Setter' s Bool -> Bool -> m () infixr 4 Source #

(||!=) :: MonadState s m => Setter' s Bool -> Bool -> m () infixr 4 Source #

(<>!=) :: (MonadState s m, Monoid a) => Setter' s a -> a -> m () infixr 4 Source #

Types

data Zooming (m :: Type -> Type) c a #

Instances

Instances details

Monad m => Functor (Zooming m c)
Instance details Defined in Lens.Family.State.Zoom Methods fmap :: (a -> b) -> Zooming m c a -> Zooming m c b # (<$) :: a -> Zooming m c b -> Zooming m c a #
(Monoid c, Monad m) => Applicative (Zooming m c)
Instance details Defined in Lens.Family.State.Zoom Methods pure :: a -> Zooming m c a # (<>) :: Zooming m c (a -> b) -> Zooming m c a -> Zooming m c b # liftA2 :: (a -> b -> c0) -> Zooming m c a -> Zooming m c b -> Zooming m c c0 # (>) :: Zooming m c a -> Zooming m c b -> Zooming m c b # (<*) :: Zooming m c a -> Zooming m c b -> Zooming m c a #

Re-exports

type LensLike (f :: Type -> Type) s t a b = (a -> f b) -> s -> f t #

type LensLike' (f :: Type -> Type) s a = (a -> f a) -> s -> f s #

type FoldLike r s t a b = LensLike (Constant r :: Type -> Type) s t a b #

data Constant a (b :: k) #

Constant functor.

Instances

Instances details

Bitraversable (Constant :: Type -> Type -> Type)
Instance details Defined in Data.Functor.Constant Methods bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> Constant a b -> f (Constant c d) #
Bifoldable (Constant :: Type -> Type -> Type)
Instance details Defined in Data.Functor.Constant Methods bifold :: Monoid m => Constant m m -> m # bifoldMap :: Monoid m => (a -> m) -> (b -> m) -> Constant a b -> m # bifoldr :: (a -> c -> c) -> (b -> c -> c) -> c -> Constant a b -> c # bifoldl :: (c -> a -> c) -> (c -> b -> c) -> c -> Constant a b -> c #
Bifunctor (Constant :: Type -> Type -> Type)
Instance details Defined in Data.Functor.Constant Methods bimap :: (a -> b) -> (c -> d) -> Constant a c -> Constant b d # first :: (a -> b) -> Constant a c -> Constant b c # second :: (b -> c) -> Constant a b -> Constant a c #
Eq2 (Constant :: Type -> Type -> Type)
Instance details Defined in Data.Functor.Constant Methods liftEq2 :: (a -> b -> Bool) -> (c -> d -> Bool) -> Constant a c -> Constant b d -> Bool #
Ord2 (Constant :: Type -> Type -> Type)
Instance details Defined in Data.Functor.Constant Methods liftCompare2 :: (a -> b -> Ordering) -> (c -> d -> Ordering) -> Constant a c -> Constant b d -> Ordering #
Read2 (Constant :: Type -> Type -> Type)
Instance details Defined in Data.Functor.Constant Methods liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (Constant a b) # liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [Constant a b] # liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (Constant a b) # liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [Constant a b] #
Show2 (Constant :: Type -> Type -> Type)
Instance details Defined in Data.Functor.Constant Methods liftShowsPrec2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> Int -> Constant a b -> ShowS # liftShowList2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> [Constant a b] -> ShowS #
Functor (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods fmap :: (a0 -> b) -> Constant a a0 -> Constant a b # (<$) :: a0 -> Constant a b -> Constant a a0 #
Monoid a => Applicative (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods pure :: a0 -> Constant a a0 # (<>) :: Constant a (a0 -> b) -> Constant a a0 -> Constant a b # liftA2 :: (a0 -> b -> c) -> Constant a a0 -> Constant a b -> Constant a c # (>) :: Constant a a0 -> Constant a b -> Constant a b # (<*) :: Constant a a0 -> Constant a b -> Constant a a0 #
Foldable (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods fold :: Monoid m => Constant a m -> m # foldMap :: Monoid m => (a0 -> m) -> Constant a a0 -> m # foldMap' :: Monoid m => (a0 -> m) -> Constant a a0 -> m # foldr :: (a0 -> b -> b) -> b -> Constant a a0 -> b # foldr' :: (a0 -> b -> b) -> b -> Constant a a0 -> b # foldl :: (b -> a0 -> b) -> b -> Constant a a0 -> b # foldl' :: (b -> a0 -> b) -> b -> Constant a a0 -> b # foldr1 :: (a0 -> a0 -> a0) -> Constant a a0 -> a0 # foldl1 :: (a0 -> a0 -> a0) -> Constant a a0 -> a0 # toList :: Constant a a0 -> [a0] # null :: Constant a a0 -> Bool # length :: Constant a a0 -> Int # elem :: Eq a0 => a0 -> Constant a a0 -> Bool # maximum :: Ord a0 => Constant a a0 -> a0 # minimum :: Ord a0 => Constant a a0 -> a0 # sum :: Num a0 => Constant a a0 -> a0 # product :: Num a0 => Constant a a0 -> a0 #
Traversable (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods traverse :: Applicative f => (a0 -> f b) -> Constant a a0 -> f (Constant a b) # sequenceA :: Applicative f => Constant a (f a0) -> f (Constant a a0) # mapM :: Monad m => (a0 -> m b) -> Constant a a0 -> m (Constant a b) # sequence :: Monad m => Constant a (m a0) -> m (Constant a a0) #
Contravariant (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods contramap :: (a0 -> b) -> Constant a b -> Constant a a0 # (>$) :: b -> Constant a b -> Constant a a0 #
Eq a => Eq1 (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods liftEq :: (a0 -> b -> Bool) -> Constant a a0 -> Constant a b -> Bool #
Ord a => Ord1 (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods liftCompare :: (a0 -> b -> Ordering) -> Constant a a0 -> Constant a b -> Ordering #
Read a => Read1 (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods liftReadsPrec :: (Int -> ReadS a0) -> ReadS [a0] -> Int -> ReadS (Constant a a0) # liftReadList :: (Int -> ReadS a0) -> ReadS [a0] -> ReadS [Constant a a0] # liftReadPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec (Constant a a0) # liftReadListPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec [Constant a a0] #
Show a => Show1 (Constant a :: Type -> Type)
Instance details Defined in Data.Functor.Constant Methods liftShowsPrec :: (Int -> a0 -> ShowS) -> ([a0] -> ShowS) -> Int -> Constant a a0 -> ShowS # liftShowList :: (Int -> a0 -> ShowS) -> ([a0] -> ShowS) -> [Constant a a0] -> ShowS #
Phantom (Constant a :: Type -> Type)
Instance details Defined in Lens.Family.Phantom Methods coerce :: Constant a a0 -> Constant a b
Eq a => Eq (Constant a b)
Instance details Defined in Data.Functor.Constant Methods (==) :: Constant a b -> Constant a b -> Bool # (/=) :: Constant a b -> Constant a b -> Bool #
Ord a => Ord (Constant a b)
Instance details Defined in Data.Functor.Constant Methods compare :: Constant a b -> Constant a b -> Ordering # (<) :: Constant a b -> Constant a b -> Bool # (<=) :: Constant a b -> Constant a b -> Bool # (>) :: Constant a b -> Constant a b -> Bool # (>=) :: Constant a b -> Constant a b -> Bool # max :: Constant a b -> Constant a b -> Constant a b # min :: Constant a b -> Constant a b -> Constant a b #
Read a => Read (Constant a b)
Instance details Defined in Data.Functor.Constant Methods readsPrec :: Int -> ReadS (Constant a b) # readList :: ReadS [Constant a b] # readPrec :: ReadPrec (Constant a b) # readListPrec :: ReadPrec [Constant a b] #
Show a => Show (Constant a b)
Instance details Defined in Data.Functor.Constant Methods showsPrec :: Int -> Constant a b -> ShowS # show :: Constant a b -> String # showList :: [Constant a b] -> ShowS #
Semigroup a => Semigroup (Constant a b)
Instance details Defined in Data.Functor.Constant Methods (<>) :: Constant a b -> Constant a b -> Constant a b # sconcat :: NonEmpty (Constant a b) -> Constant a b # stimes :: Integral b0 => b0 -> Constant a b -> Constant a b #
Monoid a => Monoid (Constant a b)
Instance details Defined in Data.Functor.Constant Methods mempty :: Constant a b # mappend :: Constant a b -> Constant a b -> Constant a b # mconcat :: [Constant a b] -> Constant a b #

type Setter s t a b = forall f. Identical f => LensLike f s t a b Source #

type Setter' s a = forall f. Identical f => LensLike' f s a Source #

class (Traversable f, Applicative f) => Identical (f :: Type -> Type) #

Minimal complete definition

extract

Instances

Instances details

Identical Identity
Instance details Defined in Lens.Family.Identical Methods extract :: Identity a -> a
Identical f => Identical (Backwards f)
Instance details Defined in Lens.Family.Identical Methods extract :: Backwards f a -> a
(Identical f, Identical g) => Identical (Compose f g)
Instance details Defined in Lens.Family.Identical Methods extract :: Compose f g a -> a

data StateT s (m :: Type -> Type) a #

A state transformer monad parameterized by:

s - The state.
m - The inner monad.

The return function leaves the state unchanged, while >>= uses the final state of the first computation as the initial state of the second.

Instances

Instances details

Monad m => MonadState s (StateT s m)
Instance details Defined in Control.Monad.State.Class Methods get :: StateT s m s # put :: s -> StateT s m () # state :: (s -> (a, s)) -> StateT s m a #
MonadTrans (StateT s)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods lift :: Monad m => m a -> StateT s m a #
Monad m => Monad (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods (>>=) :: StateT s m a -> (a -> StateT s m b) -> StateT s m b # (>>) :: StateT s m a -> StateT s m b -> StateT s m b # return :: a -> StateT s m a #
Functor m => Functor (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods fmap :: (a -> b) -> StateT s m a -> StateT s m b # (<$) :: a -> StateT s m b -> StateT s m a #
MonadFix m => MonadFix (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods mfix :: (a -> StateT s m a) -> StateT s m a #
MonadFail m => MonadFail (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods fail :: String -> StateT s m a #
(Functor m, Monad m) => Applicative (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods pure :: a -> StateT s m a # (<>) :: StateT s m (a -> b) -> StateT s m a -> StateT s m b # liftA2 :: (a -> b -> c) -> StateT s m a -> StateT s m b -> StateT s m c # (>) :: StateT s m a -> StateT s m b -> StateT s m b # (<*) :: StateT s m a -> StateT s m b -> StateT s m a #
Contravariant m => Contravariant (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods contramap :: (a -> b) -> StateT s m b -> StateT s m a # (>$) :: b -> StateT s m b -> StateT s m a #
MonadIO m => MonadIO (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods liftIO :: IO a -> StateT s m a #
(Functor m, MonadPlus m) => Alternative (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods empty :: StateT s m a # (<\|>) :: StateT s m a -> StateT s m a -> StateT s m a # some :: StateT s m a -> StateT s m [a] # many :: StateT s m a -> StateT s m [a] #
MonadPlus m => MonadPlus (StateT s m)
Instance details Defined in Control.Monad.Trans.State.Lazy Methods mzero :: StateT s m a # mplus :: StateT s m a -> StateT s m a -> StateT s m a #

class Monad m => MonadState s (m :: Type -> Type) | m -> s #

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

Minimal complete definition

state | get, put

Instances

Instances details

MonadState s m => MonadState s (MaybeT m)
Instance details Defined in Control.Monad.State.Class Methods get :: MaybeT m s # put :: s -> MaybeT m () # state :: (s -> (a, s)) -> MaybeT m a #
MonadState s m => MonadState s (ListT m)
Instance details Defined in Control.Monad.State.Class Methods get :: ListT m s # put :: s -> ListT m () # state :: (s -> (a, s)) -> ListT 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, 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 #
Monad m => MonadState s (StateT s m)
Instance details Defined in Control.Monad.State.Class Methods get :: StateT s m s # put :: s -> StateT s m () # state :: (s -> (a, s)) -> StateT s m a #
Monad m => MonadState s (StateT s m)
Instance details Defined in Control.Monad.State.Class Methods get :: StateT s m s # put :: s -> StateT s m () # state :: (s -> (a, s)) -> StateT s m a #
MonadState s m => MonadState s (ReaderT r m)
Instance details Defined in Control.Monad.State.Class Methods get :: ReaderT r m s # put :: s -> ReaderT r m () # state :: (s -> (a, s)) -> ReaderT r m a #
MonadState s m => MonadState s (IdentityT m)
Instance details Defined in Control.Monad.State.Class Methods get :: IdentityT m s # put :: s -> IdentityT m () # state :: (s -> (a, s)) -> IdentityT m a #
MonadState s m => MonadState s (ExceptT e m)	Since: mtl-2.2
Instance details Defined in Control.Monad.State.Class Methods get :: ExceptT e m s # put :: s -> ExceptT e m () # state :: (s -> (a, s)) -> ExceptT e m a #
(Error e, MonadState s m) => MonadState s (ErrorT e m)
Instance details Defined in Control.Monad.State.Class Methods get :: ErrorT e m s # put :: s -> ErrorT e m () # state :: (s -> (a, s)) -> ErrorT e m a #
MonadState s m => MonadState s (ContT r m)
Instance details Defined in Control.Monad.State.Class Methods get :: ContT r m s # put :: s -> ContT r m () # state :: (s -> (a, s)) -> ContT r m a #
(Monad m, Monoid w) => MonadState s (RWST r w s m)
Instance details Defined in Control.Monad.State.Class Methods get :: RWST r w s m s # put :: s -> RWST r w s m () # state :: (s -> (a, s)) -> RWST r w s m a #
(Monad m, Monoid w) => MonadState s (RWST r w s m)
Instance details Defined in Control.Monad.State.Class Methods get :: RWST r w s m s # put :: s -> RWST r w s m () # state :: (s -> (a, s)) -> RWST r w s m a #

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.