lens-5.0.1: Lenses, Folds and Traversals
Copyright (C) 2012-16 Edward Kmett
License BSD-style (see the file LICENSE)
Maintainer Edward Kmett <ekmett@gmail.com>
Stability provisional
Portability Rank2Types
Safe Haskell Trustworthy
Language Haskell2010

Control.Lens.Setter

Description

A Setter s t a b is a generalization of fmap from Functor . It allows you to map into a structure and change out the contents, but it isn't strong enough to allow you to enumerate those contents. Starting with fmap :: Functor f => (a -> b) -> f a -> f b we monomorphize the type to obtain (a -> b) -> s -> t and then decorate it with Identity to obtain:

type Setter s t a b = (a -> Identity b) -> s -> Identity t

Every Traversal is a valid Setter , since Identity is Applicative .

Everything you can do with a Functor , you can do with a Setter . There are combinators that generalize fmap and ( <$ ).

Synopsis

Setters

type Setter s t a b = forall f. Settable f => (a -> f b) -> s -> f t Source #

The only LensLike law that can apply to a Setter l is that

set l y (set l x a) ≡ set l y a

You can't view a Setter in general, so the other two laws are irrelevant.

However, two Functor laws apply to a Setter :

over l idid
over l f . over l g ≡ over l (f . g)

These can be stated more directly:

l purepure
l f . untainted . l g ≡ l (f . untainted . g)

You can compose a Setter with a Lens or a Traversal using ( . ) from the Prelude and the result is always only a Setter and nothing more.

>>> over traverse f [a,b,c,d]
[f a,f b,f c,f d]
>>> over _1 f (a,b)
(f a,b)
>>> over (traverse._1) f [(a,b),(c,d)]
[(f a,b),(f c,d)]
>>> over both f (a,b)
(f a,f b)
>>> over (traverse.both) f [(a,b),(c,d)]
[(f a,f b),(f c,f d)]

type Setter' s a = Setter s s a a Source #

A Setter' is just a Setter that doesn't change the types.

These are particularly common when talking about monomorphic containers. e.g.

sets Data.Text.map :: Setter' Text Char
type Setter' = Simple Setter

type IndexedSetter i s t a b = forall f p. ( Indexable i p, Settable f) => p a (f b) -> s -> f t Source #

Every IndexedSetter is a valid Setter .

The Setter laws are still required to hold.

type ASetter s t a b = (a -> Identity b) -> s -> Identity t Source #

Running a Setter instantiates it to a concrete type.

When consuming a setter directly to perform a mapping, you can use this type, but most user code will not need to use this type.

type ASetter' s a = ASetter s s a a Source #

This is a useful alias for use when consuming a Setter' .

Most user code will never have to use this type.

type ASetter' = Simple ASetter

type AnIndexedSetter i s t a b = Indexed i a ( Identity b) -> s -> Identity t Source #

Running an IndexedSetter instantiates it to a concrete type.

When consuming a setter directly to perform a mapping, you can use this type, but most user code will not need to use this type.

type Setting p s t a b = p a ( Identity b) -> s -> Identity t Source #

This is a convenient alias when defining highly polymorphic code that takes both ASetter and AnIndexedSetter as appropriate. If a function takes this it is expecting one of those two things based on context.

type Setting' p s a = Setting p s s a a Source #

This is a convenient alias when defining highly polymorphic code that takes both ASetter' and AnIndexedSetter' as appropriate. If a function takes this it is expecting one of those two things based on context.

Building Setters

sets :: ( Profunctor p, Profunctor q, Settable f) => (p a b -> q s t) -> Optical p q f s t a b Source #

Build a Setter , IndexedSetter or IndexPreservingSetter depending on your choice of Profunctor .

sets :: ((a -> b) -> s -> t) -> Setter s t a b

setting :: ((a -> b) -> s -> t) -> IndexPreservingSetter s t a b Source #

Build an index-preserving Setter from a map-like function.

Your supplied function f is required to satisfy:

f idid
f g . f h ≡ f (g . h)

Equational reasoning:

setting . overid
over . settingid

Another way to view sets is that it takes a "semantic editor combinator" and transforms it into a Setter .

setting :: ((a -> b) -> s -> t) -> Setter s t a b

Common Setters

mapped :: Functor f => Setter (f a) (f b) a b Source #

This Setter can be used to map over all of the values in a Functor .

fmapover mapped
fmapDefaultover traverse
(<$) ≡ set mapped
>>> over mapped f [a,b,c]
[f a,f b,f c]
>>> over mapped (+1) [1,2,3]
[2,3,4]
>>> set mapped x [a,b,c]
[x,x,x]
>>> [[a,b],[c]] & mapped.mapped +~ x
[[a + x,b + x],[c + x]]
>>> over (mapped._2) length [("hello","world"),("leaders","!!!")]
[("hello",5),("leaders",3)]
mapped :: Functor f => Setter (f a) (f b) a b

If you want an IndexPreservingSetter use setting fmap .

lifted :: Monad m => Setter (m a) (m b) a b Source #

This setter can be used to modify all of the values in a Monad .

You sometimes have to use this rather than mapped -- due to temporary insanity Functor was not a superclass of Monad until GHC 7.10.

liftMover lifted
>>> over lifted f [a,b,c]
[f a,f b,f c]
>>> set lifted b (Just a)
Just b

If you want an IndexPreservingSetter use setting liftM .

contramapped :: Contravariant f => Setter (f b) (f a) a b Source #

This Setter can be used to map over all of the inputs to a Contravariant .

contramapover contramapped
>>> getPredicate (over contramapped (*2) (Predicate even)) 5
True
>>> getOp (over contramapped (*5) (Op show)) 100
"500"
>>> Prelude.map ($ 1) $ over (mapped . _Unwrapping' Op . contramapped) (*12) [(*2),(+1),(^3)]
[24,13,1728]

argument :: Profunctor p => Setter (p b r) (p a r) a b Source #

This Setter can be used to map over the input of a Profunctor .

The most common Profunctor to use this with is (->) .

>>> (argument %~ f) g x
g (f x)
>>> (argument %~ show) length [1,2,3]
7
>>> (argument %~ f) h x y
h (f x) y

Map over the argument of the result of a function -- i.e., its second argument:

>>> (mapped.argument %~ f) h x y
h x (f y)
argument :: Setter (b -> r) (a -> r) a b

Functional Combinators

over :: ASetter s t a b -> (a -> b) -> s -> t Source #

Modify the target of a Lens or all the targets of a Setter or Traversal with a function.

fmapover mapped
fmapDefaultover traverse
sets . overid
over . setsid

Given any valid Setter l , you can also rely on the law:

over l f . over l g = over l (f . g)

e.g.

>>> over mapped f (over mapped g [a,b,c]) == over mapped (f . g) [a,b,c]
True

Another way to view over is to say that it transforms a Setter into a "semantic editor combinator".

>>> over mapped f (Just a)
Just (f a)
>>> over mapped (*10) [1,2,3]
[10,20,30]
>>> over _1 f (a,b)
(f a,b)
>>> over _1 show (10,20)
("10",20)
over :: Setter s t a b -> (a -> b) -> s -> t
over :: ASetter s t a b -> (a -> b) -> s -> t

set :: ASetter s t a b -> b -> s -> t Source #

Replace the target of a Lens or all of the targets of a Setter or Traversal with a constant value.

(<$) ≡ set mapped
>>> set _2 "hello" (1,())
(1,"hello")
>>> set mapped () [1,2,3,4]
[(),(),(),()]

Note: Attempting to set a Fold or Getter will fail at compile time with an relatively nice error message.

set :: Setter s t a b    -> b -> s -> t
set :: Iso s t a b       -> b -> s -> t
set :: Lens s t a b      -> b -> s -> t
set :: Traversal s t a b -> b -> s -> t

(.~) :: ASetter s t a b -> b -> s -> t infixr 4 Source #

Replace the target of a Lens or all of the targets of a Setter or Traversal with a constant value.

This is an infix version of set , provided for consistency with ( .= ).

f <$ a ≡ mapped .~ f $ a
>>> (a,b,c,d) & _4 .~ e
(a,b,c,e)
>>> (42,"world") & _1 .~ "hello"
("hello","world")
>>> (a,b) & both .~ c
(c,c)
(.~) :: Setter s t a b    -> b -> s -> t
(.~) :: Iso s t a b       -> b -> s -> t
(.~) :: Lens s t a b      -> b -> s -> t
(.~) :: Traversal s t a b -> b -> s -> t

(%~) :: ASetter s t a b -> (a -> b) -> s -> t infixr 4 Source #

Modifies the target of a Lens or all of the targets of a Setter or Traversal with a user supplied function.

This is an infix version of over .

fmap f ≡ mapped %~ f
fmapDefault f ≡ traverse %~ f
>>> (a,b,c) & _3 %~ f
(a,b,f c)
>>> (a,b) & both %~ f
(f a,f b)
>>> _2 %~ length $ (1,"hello")
(1,5)
>>> traverse %~ f $ [a,b,c]
[f a,f b,f c]
>>> traverse %~ even $ [1,2,3]
[False,True,False]
>>> traverse.traverse %~ length $ [["hello","world"],["!!!"]]
[[5,5],[3]]
(%~) :: Setter s t a b    -> (a -> b) -> s -> t
(%~) :: Iso s t a b       -> (a -> b) -> s -> t
(%~) :: Lens s t a b      -> (a -> b) -> s -> t
(%~) :: Traversal s t a b -> (a -> b) -> s -> t

(+~) :: Num a => ASetter s t a a -> a -> s -> t infixr 4 Source #

Increment the target(s) of a numerically valued Lens , Setter or Traversal .

>>> (a,b) & _1 +~ c
(a + c,b)
>>> (a,b) & both +~ c
(a + c,b + c)
>>> (1,2) & _2 +~ 1
(1,3)
>>> [(a,b),(c,d)] & traverse.both +~ e
[(a + e,b + e),(c + e,d + e)]
(+~) :: Num a => Setter' s a    -> a -> s -> s
(+~) :: Num a => Iso' s a       -> a -> s -> s
(+~) :: Num a => Lens' s a      -> a -> s -> s
(+~) :: Num a => Traversal' s a -> a -> s -> s

(-~) :: Num a => ASetter s t a a -> a -> s -> t infixr 4 Source #

Decrement the target(s) of a numerically valued Lens , Iso , Setter or Traversal .

>>> (a,b) & _1 -~ c
(a - c,b)
>>> (a,b) & both -~ c
(a - c,b - c)
>>> _1 -~ 2 $ (1,2)
(-1,2)
>>> mapped.mapped -~ 1 $ [[4,5],[6,7]]
[[3,4],[5,6]]
(-~) :: Num a => Setter' s a    -> a -> s -> s
(-~) :: Num a => Iso' s a       -> a -> s -> s
(-~) :: Num a => Lens' s a      -> a -> s -> s
(-~) :: Num a => Traversal' s a -> a -> s -> s

(*~) :: Num a => ASetter s t a a -> a -> s -> t infixr 4 Source #

Multiply the target(s) of a numerically valued Lens , Iso , Setter or Traversal .

>>> (a,b) & _1 *~ c
(a * c,b)
>>> (a,b) & both *~ c
(a * c,b * c)
>>> (1,2) & _2 *~ 4
(1,8)
>>> Just 24 & mapped *~ 2
Just 48
(*~) :: Num a => Setter' s a    -> a -> s -> s
(*~) :: Num a => Iso' s a       -> a -> s -> s
(*~) :: Num a => Lens' s a      -> a -> s -> s
(*~) :: Num a => Traversal' s a -> a -> s -> s

(//~) :: Fractional a => ASetter s t a a -> a -> s -> t infixr 4 Source #

Divide the target(s) of a numerically valued Lens , Iso , Setter or Traversal .

>>> (a,b) & _1 //~ c
(a / c,b)
>>> (a,b) & both //~ c
(a / c,b / c)
>>> ("Hawaii",10) & _2 //~ 2
("Hawaii",5.0)
(//~) :: Fractional a => Setter' s a    -> a -> s -> s
(//~) :: Fractional a => Iso' s a       -> a -> s -> s
(//~) :: Fractional a => Lens' s a      -> a -> s -> s
(//~) :: Fractional a => Traversal' s a -> a -> s -> s

(^~) :: ( Num a, Integral e) => ASetter s t a a -> e -> s -> t infixr 4 Source #

Raise the target(s) of a numerically valued Lens , Setter or Traversal to a non-negative integral power.

>>> (1,3) & _2 ^~ 2
(1,9)
(^~) :: (Num a, Integral e) => Setter' s a    -> e -> s -> s
(^~) :: (Num a, Integral e) => Iso' s a       -> e -> s -> s
(^~) :: (Num a, Integral e) => Lens' s a      -> e -> s -> s
(^~) :: (Num a, Integral e) => Traversal' s a -> e -> s -> s

(^^~) :: ( Fractional a, Integral e) => ASetter s t a a -> e -> s -> t infixr 4 Source #

Raise the target(s) of a fractionally valued Lens , Setter or Traversal to an integral power.

>>> (1,2) & _2 ^^~ (-1)
(1,0.5)
(^^~) :: (Fractional a, Integral e) => Setter' s a    -> e -> s -> s
(^^~) :: (Fractional a, Integral e) => Iso' s a       -> e -> s -> s
(^^~) :: (Fractional a, Integral e) => Lens' s a      -> e -> s -> s
(^^~) :: (Fractional a, Integral e) => Traversal' s a -> e -> s -> s

(**~) :: Floating a => ASetter s t a a -> a -> s -> t infixr 4 Source #

Raise the target(s) of a floating-point valued Lens , Setter or Traversal to an arbitrary power.

>>> (a,b) & _1 **~ c
(a**c,b)
>>> (a,b) & both **~ c
(a**c,b**c)
>>> _2 **~ 10 $ (3,2)
(3,1024.0)
(**~) :: Floating a => Setter' s a    -> a -> s -> s
(**~) :: Floating a => Iso' s a       -> a -> s -> s
(**~) :: Floating a => Lens' s a      -> a -> s -> s
(**~) :: Floating a => Traversal' s a -> a -> s -> s

(||~) :: ASetter s t Bool Bool -> Bool -> s -> t infixr 4 Source #

Logically || the target(s) of a Bool -valued Lens or Setter .

>>> both ||~ True $ (False,True)
(True,True)
>>> both ||~ False $ (False,True)
(False,True)
(||~) :: Setter' s Bool    -> Bool -> s -> s
(||~) :: Iso' s Bool       -> Bool -> s -> s
(||~) :: Lens' s Bool      -> Bool -> s -> s
(||~) :: Traversal' s Bool -> Bool -> s -> s

(<>~) :: Semigroup a => ASetter s t a a -> a -> s -> t infixr 4 Source #

Modify the target of a Semigroup value by using ( <> ) .

>>> (Sum a,b) & _1 <>~ Sum c
(Sum {getSum = a + c},b)
>>> (Sum a,Sum b) & both <>~ Sum c
(Sum {getSum = a + c},Sum {getSum = b + c})
>>> both <>~ "!!!" $ ("hello","world")
("hello!!!","world!!!")
(<>~) :: Semigroup a => Setter s t a a    -> a -> s -> t
(<>~) :: Semigroup a => Iso s t a a       -> a -> s -> t
(<>~) :: Semigroup a => Lens s t a a      -> a -> s -> t
(<>~) :: Semigroup a => Traversal s t a a -> a -> s -> t

(&&~) :: ASetter s t Bool Bool -> Bool -> s -> t infixr 4 Source #

Logically && the target(s) of a Bool -valued Lens or Setter .

>>> both &&~ True $ (False, True)
(False,True)
>>> both &&~ False $ (False, True)
(False,False)
(&&~) :: Setter' s Bool    -> Bool -> s -> s
(&&~) :: Iso' s Bool       -> Bool -> s -> s
(&&~) :: Lens' s Bool      -> Bool -> s -> s
(&&~) :: Traversal' s Bool -> Bool -> s -> s

(<.~) :: ASetter s t a b -> b -> s -> (b, t) infixr 4 Source #

Set with pass-through.

This is mostly present for consistency, but may be useful for chaining assignments.

If you do not need a copy of the intermediate result, then using l .~ t directly is a good idea.

>>> (a,b) & _1 <.~ c
(c,(c,b))
>>> ("good","morning","vietnam") & _3 <.~ "world"
("world",("good","morning","world"))
>>> (42,Map.fromList [("goodnight","gracie")]) & _2.at "hello" <.~ Just "world"
(Just "world",(42,fromList [("goodnight","gracie"),("hello","world")]))
(<.~) :: Setter s t a b    -> b -> s -> (b, t)
(<.~) :: Iso s t a b       -> b -> s -> (b, t)
(<.~) :: Lens s t a b      -> b -> s -> (b, t)
(<.~) :: Traversal s t a b -> b -> s -> (b, t)

(?~) :: ASetter s t a ( Maybe b) -> b -> s -> t infixr 4 Source #

Set the target of a Lens , Traversal or Setter to Just a value.

l ?~ t ≡ set l (Just t)
>>> Nothing & id ?~ a
Just a
>>> Map.empty & at 3 ?~ x
fromList [(3,x)]

?~ can be used type-changily:

>>> ('a', ('b', 'c')) & _2.both ?~ 'x'
('a',(Just 'x',Just 'x'))
(?~) :: Setter s t a (Maybe b)    -> b -> s -> t
(?~) :: Iso s t a (Maybe b)       -> b -> s -> t
(?~) :: Lens s t a (Maybe b)      -> b -> s -> t
(?~) :: Traversal s t a (Maybe b) -> b -> s -> t

(<?~) :: ASetter s t a ( Maybe b) -> b -> s -> (b, t) infixr 4 Source #

Set to Just a value with pass-through.

This is mostly present for consistency, but may be useful for for chaining assignments.

If you do not need a copy of the intermediate result, then using l ?~ d directly is a good idea.

>>> import qualified Data.Map as Map
>>> _2.at "hello" <?~ "world" $ (42,Map.fromList [("goodnight","gracie")])
("world",(42,fromList [("goodnight","gracie"),("hello","world")]))
(<?~) :: Setter s t a (Maybe b)    -> b -> s -> (b, t)
(<?~) :: Iso s t a (Maybe b)       -> b -> s -> (b, t)
(<?~) :: Lens s t a (Maybe b)      -> b -> s -> (b, t)
(<?~) :: Traversal s t a (Maybe b) -> b -> s -> (b, t)

State Combinators

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

Replace the target of a Lens or all of the targets of a Setter or Traversal in our monadic state with a new value, irrespective of the old.

This is an alias for ( .= ).

>>> execState (do assign _1 c; assign _2 d) (a,b)
(c,d)
>>> execState (both .= c) (a,b)
(c,c)
assign :: MonadState s m => Iso' s a       -> a -> m ()
assign :: MonadState s m => Lens' s a      -> a -> m ()
assign :: MonadState s m => Traversal' s a -> a -> m ()
assign :: MonadState s m => Setter' s a    -> a -> m ()

modifying :: MonadState s m => ASetter s s a b -> (a -> b) -> m () Source #

This is an alias for ( %= ).

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

Replace the target of a Lens or all of the targets of a Setter or Traversal in our monadic state with a new value, irrespective of the old.

This is an infix version of assign .

>>> execState (do _1 .= c; _2 .= d) (a,b)
(c,d)
>>> execState (both .= c) (a,b)
(c,c)
(.=) :: MonadState s m => Iso' s a       -> a -> m ()
(.=) :: MonadState s m => Lens' s a      -> a -> m ()
(.=) :: MonadState s m => Traversal' s a -> a -> m ()
(.=) :: MonadState s m => Setter' s a    -> a -> m ()

It puts the state in the monad or it gets the hose again.

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

Map over the target of a Lens or all of the targets of a Setter or Traversal in our monadic state.

>>> execState (do _1 %= f;_2 %= g) (a,b)
(f a,g b)
>>> execState (do both %= f) (a,b)
(f a,f b)
(%=) :: MonadState s m => Iso' s a       -> (a -> a) -> m ()
(%=) :: MonadState s m => Lens' s a      -> (a -> a) -> m ()
(%=) :: MonadState s m => Traversal' s a -> (a -> a) -> m ()
(%=) :: MonadState s m => Setter' s a    -> (a -> a) -> m ()
(%=) :: MonadState s m => ASetter s s a b -> (a -> b) -> m ()

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

Modify the target(s) of a Lens' , Iso , Setter or Traversal by adding a value.

Example:

fresh :: MonadState Int m => m Int
fresh = do
  id += 1
  use id
>>> execState (do _1 += c; _2 += d) (a,b)
(a + c,b + d)
>>> execState (do _1.at 1.non 0 += 10) (Map.fromList [(2,100)],"hello")
(fromList [(1,10),(2,100)],"hello")
(+=) :: (MonadState s m, Num a) => Setter' s a    -> a -> m ()
(+=) :: (MonadState s m, Num a) => Iso' s a       -> a -> m ()
(+=) :: (MonadState s m, Num a) => Lens' s a      -> a -> m ()
(+=) :: (MonadState s m, Num a) => Traversal' s a -> a -> m ()

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

Modify the target(s) of a Lens' , Iso , Setter or Traversal by subtracting a value.

>>> execState (do _1 -= c; _2 -= d) (a,b)
(a - c,b - d)
(-=) :: (MonadState s m, Num a) => Setter' s a    -> a -> m ()
(-=) :: (MonadState s m, Num a) => Iso' s a       -> a -> m ()
(-=) :: (MonadState s m, Num a) => Lens' s a      -> a -> m ()
(-=) :: (MonadState s m, Num a) => Traversal' s a -> a -> m ()

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

Modify the target(s) of a Lens' , Iso , Setter or Traversal by multiplying by value.

>>> execState (do _1 *= c; _2 *= d) (a,b)
(a * c,b * d)
(*=) :: (MonadState s m, Num a) => Setter' s a    -> a -> m ()
(*=) :: (MonadState s m, Num a) => Iso' s a       -> a -> m ()
(*=) :: (MonadState s m, Num a) => Lens' s a      -> a -> m ()
(*=) :: (MonadState s m, Num a) => Traversal' s a -> a -> m ()

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

Modify the target(s) of a Lens' , Iso , Setter or Traversal by dividing by a value.

>>> execState (do _1 //= c; _2 //= d) (a,b)
(a / c,b / d)
(//=) :: (MonadState s m, Fractional a) => Setter' s a    -> a -> m ()
(//=) :: (MonadState s m, Fractional a) => Iso' s a       -> a -> m ()
(//=) :: (MonadState s m, Fractional a) => Lens' s a      -> a -> m ()
(//=) :: (MonadState s m, Fractional a) => Traversal' s a -> a -> m ()

(^=) :: ( MonadState s m, Num a, Integral e) => ASetter' s a -> e -> m () infix 4 Source #

Raise the target(s) of a numerically valued Lens , Setter or Traversal to a non-negative integral power.

(^=) ::  (MonadState s m, Num a, Integral e) => Setter' s a    -> e -> m ()
(^=) ::  (MonadState s m, Num a, Integral e) => Iso' s a       -> e -> m ()
(^=) ::  (MonadState s m, Num a, Integral e) => Lens' s a      -> e -> m ()
(^=) ::  (MonadState s m, Num a, Integral e) => Traversal' s a -> e -> m ()

(^^=) :: ( MonadState s m, Fractional a, Integral e) => ASetter' s a -> e -> m () infix 4 Source #

Raise the target(s) of a numerically valued Lens , Setter or Traversal to an integral power.

(^^=) ::  (MonadState s m, Fractional a, Integral e) => Setter' s a    -> e -> m ()
(^^=) ::  (MonadState s m, Fractional a, Integral e) => Iso' s a       -> e -> m ()
(^^=) ::  (MonadState s m, Fractional a, Integral e) => Lens' s a      -> e -> m ()
(^^=) ::  (MonadState s m, Fractional a, Integral e) => Traversal' s a -> e -> m ()

(**=) :: ( MonadState s m, Floating a) => ASetter' s a -> a -> m () infix 4 Source #

Raise the target(s) of a numerically valued Lens , Setter or Traversal to an arbitrary power

>>> execState (do _1 **= c; _2 **= d) (a,b)
(a**c,b**d)
(**=) ::  (MonadState s m, Floating a) => Setter' s a    -> a -> m ()
(**=) ::  (MonadState s m, Floating a) => Iso' s a       -> a -> m ()
(**=) ::  (MonadState s m, Floating a) => Lens' s a      -> a -> m ()
(**=) ::  (MonadState s m, Floating a) => Traversal' s a -> a -> m ()

(||=) :: MonadState s m => ASetter' s Bool -> Bool -> m () infix 4 Source #

Modify the target(s) of a Lens' , 'Iso, Setter or Traversal by taking their logical || with a value.

>>> execState (do _1 ||= True; _2 ||= False; _3 ||= True; _4 ||= False) (True,True,False,False)
(True,True,True,False)
(||=) :: MonadState s m => Setter' s Bool    -> Bool -> m ()
(||=) :: MonadState s m => Iso' s Bool       -> Bool -> m ()
(||=) :: MonadState s m => Lens' s Bool      -> Bool -> m ()
(||=) :: MonadState s m => Traversal' s Bool -> Bool -> m ()

(<>=) :: ( MonadState s m, Semigroup a) => ASetter' s a -> a -> m () infix 4 Source #

Modify the target(s) of a Lens' , Iso , Setter or Traversal by using ( <> ) .

>>> execState (do _1 <>= Sum c; _2 <>= Product d) (Sum a,Product b)
(Sum {getSum = a + c},Product {getProduct = b * d})
>>> execState (both <>= "!!!") ("hello","world")
("hello!!!","world!!!")
(<>=) :: (MonadState s m, Semigroup a) => Setter' s a -> a -> m ()
(<>=) :: (MonadState s m, Semigroup a) => Iso' s a -> a -> m ()
(<>=) :: (MonadState s m, Semigroup a) => Lens' s a -> a -> m ()
(<>=) :: (MonadState s m, Semigroup a) => Traversal' s a -> a -> m ()

(&&=) :: MonadState s m => ASetter' s Bool -> Bool -> m () infix 4 Source #

Modify the target(s) of a Lens' , Iso , Setter or Traversal by taking their logical && with a value.

>>> execState (do _1 &&= True; _2 &&= False; _3 &&= True; _4 &&= False) (True,True,False,False)
(True,False,False,False)
(&&=) :: MonadState s m => Setter' s Bool    -> Bool -> m ()
(&&=) :: MonadState s m => Iso' s Bool       -> Bool -> m ()
(&&=) :: MonadState s m => Lens' s Bool      -> Bool -> m ()
(&&=) :: MonadState s m => Traversal' s Bool -> Bool -> m ()

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

Set with pass-through

This is useful for chaining assignment without round-tripping through your Monad stack.

do x <- _2 <.= ninety_nine_bottles_of_beer_on_the_wall

If you do not need a copy of the intermediate result, then using l .= d will avoid unused binding warnings.

(<.=) :: MonadState s m => Setter s s a b    -> b -> m b
(<.=) :: MonadState s m => Iso s s a b       -> b -> m b
(<.=) :: MonadState s m => Lens s s a b      -> b -> m b
(<.=) :: MonadState s m => Traversal s s a b -> b -> m b

(?=) :: MonadState s m => ASetter s s a ( Maybe b) -> b -> m () infix 4 Source #

Replace the target of a Lens or all of the targets of a Setter or Traversal in our monadic state with Just a new value, irrespective of the old.

>>> execState (do at 1 ?= a; at 2 ?= b) Map.empty
fromList [(1,a),(2,b)]
>>> execState (do _1 ?= b; _2 ?= c) (Just a, Nothing)
(Just b,Just c)
(?=) :: MonadState s m => Iso' s (Maybe a)       -> a -> m ()
(?=) :: MonadState s m => Lens' s (Maybe a)      -> a -> m ()
(?=) :: MonadState s m => Traversal' s (Maybe a) -> a -> m ()
(?=) :: MonadState s m => Setter' s (Maybe a)    -> a -> m ()

(<?=) :: MonadState s m => ASetter s s a ( Maybe b) -> b -> m b infix 4 Source #

Set Just a value with pass-through

This is useful for chaining assignment without round-tripping through your Monad stack.

do x <- at "foo" <?= ninety_nine_bottles_of_beer_on_the_wall

If you do not need a copy of the intermediate result, then using l ?= d will avoid unused binding warnings.

(<?=) :: MonadState s m => Setter s s a (Maybe b)    -> b -> m b
(<?=) :: MonadState s m => Iso s s a (Maybe b)       -> b -> m b
(<?=) :: MonadState s m => Lens s s a (Maybe b)      -> b -> m b
(<?=) :: MonadState s m => Traversal s s a (Maybe b) -> b -> m b

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

Run a monadic action, and set all of the targets of a Lens , Setter or Traversal to its result.

(<~) :: MonadState s m => Iso s s a b       -> m b -> m ()
(<~) :: MonadState s m => Lens s s a b      -> m b -> m ()
(<~) :: MonadState s m => Traversal s s a b -> m b -> m ()
(<~) :: MonadState s m => Setter s s a b    -> m b -> m ()

As a reasonable mnemonic, this lets you store the result of a monadic action in a Lens rather than in a local variable.

do foo <- bar
   ...

will store the result in a variable, while

do foo <~ bar
   ...

will store the result in a Lens , Setter , or Traversal .

Writer Combinators

scribe :: ( MonadWriter t m, Monoid s) => ASetter s t a b -> b -> m () Source #

Write to a fragment of a larger Writer format.

passing :: MonadWriter w m => Setter w w u v -> m (a, u -> v) -> m a Source #

This is a generalization of pass that allows you to modify just a portion of the resulting MonadWriter .

ipassing :: MonadWriter w m => IndexedSetter i w w u v -> m (a, i -> u -> v) -> m a Source #

This is a generalization of pass that allows you to modify just a portion of the resulting MonadWriter with access to the index of an IndexedSetter .

censoring :: MonadWriter w m => Setter w w u v -> (u -> v) -> m a -> m a Source #

This is a generalization of censor that allows you to censor just a portion of the resulting MonadWriter .

icensoring :: MonadWriter w m => IndexedSetter i w w u v -> (i -> u -> v) -> m a -> m a Source #

This is a generalization of censor that allows you to censor just a portion of the resulting MonadWriter , with access to the index of an IndexedSetter .

Reader Combinators

locally :: MonadReader s m => ASetter s s a b -> (a -> b) -> m r -> m r Source #

Modify the value of the Reader environment associated with the target of a Setter , Lens , or Traversal .

locally l id a ≡ a
locally l f . locally l g ≡ locally l (f . g)
>>> (1,1) & locally _1 (+1) (uncurry (+))
3
>>> "," & locally ($) ("Hello" <>) (<> " world!")
"Hello, world!"
locally :: MonadReader s m => Iso s s a b       -> (a -> b) -> m r -> m r
locally :: MonadReader s m => Lens s s a b      -> (a -> b) -> m r -> m r
locally :: MonadReader s m => Traversal s s a b -> (a -> b) -> m r -> m r
locally :: MonadReader s m => Setter s s a b    -> (a -> b) -> m r -> m r

ilocally :: MonadReader s m => AnIndexedSetter i s s a b -> (i -> a -> b) -> m r -> m r Source #

This is a generalization of locally that allows one to make indexed local changes to a Reader environment associated with the target of a Setter , Lens , or Traversal .

locally l f ≡ ilocally l f . const
ilocally l f ≡ locally l f . Indexed
ilocally :: MonadReader s m => IndexedLens s s a b      -> (i -> a -> b) -> m r -> m r
ilocally :: MonadReader s m => IndexedTraversal s s a b -> (i -> a -> b) -> m r -> m r
ilocally :: MonadReader s m => IndexedSetter s s a b    -> (i -> a -> b) -> m r -> m r

Simplified State Setting

set' :: ASetter' s a -> a -> s -> s Source #

Replace the target of a Lens or all of the targets of a Setter' or Traversal with a constant value, without changing its type.

This is a type restricted version of set , which retains the type of the original.

>>> set' mapped x [a,b,c,d]
[x,x,x,x]
>>> set' _2 "hello" (1,"world")
(1,"hello")
>>> set' mapped 0 [1,2,3,4]
[0,0,0,0]

Note: Attempting to adjust set' a Fold or Getter will fail at compile time with an relatively nice error message.

set' :: Setter' s a    -> a -> s -> s
set' :: Iso' s a       -> a -> s -> s
set' :: Lens' s a      -> a -> s -> s
set' :: Traversal' s a -> a -> s -> s

Indexed Setters

imapOf :: AnIndexedSetter i s t a b -> (i -> a -> b) -> s -> t Source #

Deprecated: Use iover

Map with index. (Deprecated alias for iover ).

When you do not need access to the index, then mapOf is more liberal in what it can accept.

mapOf l ≡ imapOf l . const
imapOf :: IndexedSetter i s t a b    -> (i -> a -> b) -> s -> t
imapOf :: IndexedLens i s t a b      -> (i -> a -> b) -> s -> t
imapOf :: IndexedTraversal i s t a b -> (i -> a -> b) -> s -> t

iover :: AnIndexedSetter i s t a b -> (i -> a -> b) -> s -> t Source #

Map with index. This is an alias for imapOf .

When you do not need access to the index, then over is more liberal in what it can accept.

over l ≡ iover l . const
iover l ≡ over l . Indexed
iover :: IndexedSetter i s t a b    -> (i -> a -> b) -> s -> t
iover :: IndexedLens i s t a b      -> (i -> a -> b) -> s -> t
iover :: IndexedTraversal i s t a b -> (i -> a -> b) -> s -> t

iset :: AnIndexedSetter i s t a b -> (i -> b) -> s -> t Source #

Set with index. Equivalent to iover with the current value ignored.

When you do not need access to the index, then set is more liberal in what it can accept.

set l ≡ iset l . const
iset :: IndexedSetter i s t a b    -> (i -> b) -> s -> t
iset :: IndexedLens i s t a b      -> (i -> b) -> s -> t
iset :: IndexedTraversal i s t a b -> (i -> b) -> s -> t

imodifying :: MonadState s m => AnIndexedSetter i s s a b -> (i -> a -> b) -> m () Source #

This is an alias for ( %@= ).

isets :: ((i -> a -> b) -> s -> t) -> IndexedSetter i s t a b Source #

Build an IndexedSetter from an imap -like function.

Your supplied function f is required to satisfy:

f idid
f g . f h ≡ f (g . h)

Equational reasoning:

isets . ioverid
iover . isetsid

Another way to view isets is that it takes a "semantic editor combinator" which has been modified to carry an index and transforms it into a IndexedSetter .

(%@~) :: AnIndexedSetter i s t a b -> (i -> a -> b) -> s -> t infixr 4 Source #

Adjust every target of an IndexedSetter , IndexedLens or IndexedTraversal with access to the index.

(%@~) ≡ iover

When you do not need access to the index then ( %~ ) is more liberal in what it can accept.

l %~ f ≡ l %@~ const f
(%@~) :: IndexedSetter i s t a b    -> (i -> a -> b) -> s -> t
(%@~) :: IndexedLens i s t a b      -> (i -> a -> b) -> s -> t
(%@~) :: IndexedTraversal i s t a b -> (i -> a -> b) -> s -> t

(.@~) :: AnIndexedSetter i s t a b -> (i -> b) -> s -> t infixr 4 Source #

Replace every target of an IndexedSetter , IndexedLens or IndexedTraversal with access to the index.

(.@~) ≡ iset

When you do not need access to the index then ( .~ ) is more liberal in what it can accept.

l .~ b ≡ l .@~ const b
(.@~) :: IndexedSetter i s t a b    -> (i -> b) -> s -> t
(.@~) :: IndexedLens i s t a b      -> (i -> b) -> s -> t
(.@~) :: IndexedTraversal i s t a b -> (i -> b) -> s -> t

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

Adjust every target in the current state of an IndexedSetter , IndexedLens or IndexedTraversal with access to the index.

When you do not need access to the index then ( %= ) is more liberal in what it can accept.

l %= f ≡ l %@= const f
(%@=) :: MonadState s m => IndexedSetter i s s a b    -> (i -> a -> b) -> m ()
(%@=) :: MonadState s m => IndexedLens i s s a b      -> (i -> a -> b) -> m ()
(%@=) :: MonadState s m => IndexedTraversal i s t a b -> (i -> a -> b) -> m ()

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

Replace every target in the current state of an IndexedSetter , IndexedLens or IndexedTraversal with access to the index.

When you do not need access to the index then ( .= ) is more liberal in what it can accept.

l .= b ≡ l .@= const b
(.@=) :: MonadState s m => IndexedSetter i s s a b    -> (i -> b) -> m ()
(.@=) :: MonadState s m => IndexedLens i s s a b      -> (i -> b) -> m ()
(.@=) :: MonadState s m => IndexedTraversal i s t a b -> (i -> b) -> m ()

Arrow operators

assignA :: Arrow p => ASetter s t a b -> p s b -> p s t Source #

Run an arrow command and use the output to set all the targets of a Lens , Setter or Traversal to the result.

assignA can be used very similarly to ( <~ ), except that the type of the object being modified can change; for example:

runKleisli action ((), (), ()) where
  action =      assignA _1 (Kleisli (const getVal1))
           >>> assignA _2 (Kleisli (const getVal2))
           >>> assignA _3 (Kleisli (const getVal3))
  getVal1 :: Either String Int
  getVal1 = ...
  getVal2 :: Either String Bool
  getVal2 = ...
  getVal3 :: Either String Char
  getVal3 = ...

has the type Either String ( Int , Bool , Char )

assignA :: Arrow p => Iso s t a b       -> p s b -> p s t
assignA :: Arrow p => Lens s t a b      -> p s b -> p s t
assignA :: Arrow p => Traversal s t a b -> p s b -> p s t
assignA :: Arrow p => Setter s t a b    -> p s b -> p s t

Exported for legible error messages

newtype Identity a Source #

Identity functor and monad. (a non-strict monad)

Since: base-4.8.0.0

Constructors

Identity

Fields

Instances

Instances details
Monad Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Functor Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

MonadFix Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Applicative Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Foldable Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Traversable Identity

Since: base-4.9.0.0

Instance details

Defined in Data.Traversable

Distributive Identity
Instance details

Defined in Data.Distributive

Representable Identity
Instance details

Defined in Data.Functor.Rep

Associated Types

type Rep Identity Source #

Eq1 Identity

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Ord1 Identity

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Read1 Identity

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Show1 Identity

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Comonad Identity
Instance details

Defined in Control.Comonad

ComonadApply Identity
Instance details

Defined in Control.Comonad

NFData1 Identity

Since: deepseq-1.4.3.0

Instance details

Defined in Control.DeepSeq

Methods

liftRnf :: (a -> ()) -> Identity a -> () Source #

Hashable1 Identity
Instance details

Defined in Data.Hashable.Class

Traversable1 Identity
Instance details

Defined in Data.Semigroup.Traversable.Class

Alt Identity

Choose the first option every time. While 'choose the last option' every time is also valid, this instance satisfies more laws.

Since: semigroupoids-5.3.6

Instance details

Defined in Data.Functor.Alt

Apply Identity
Instance details

Defined in Data.Functor.Bind.Class

Bind Identity
Instance details

Defined in Data.Functor.Bind.Class

Foldable1 Identity
Instance details

Defined in Data.Semigroup.Foldable.Class

Extend Identity
Instance details

Defined in Data.Functor.Extend

Settable Identity Source #

So you can pass our Setter into combinators from other lens libraries.

Instance details

Defined in Control.Lens.Internal.Setter

FunctorWithIndex () Identity
Instance details

Defined in WithIndex

Methods

imap :: (() -> a -> b) -> Identity a -> Identity b Source #

FoldableWithIndex () Identity
Instance details

Defined in WithIndex

Methods

ifoldMap :: Monoid m => (() -> a -> m) -> Identity a -> m Source #

ifoldMap' :: Monoid m => (() -> a -> m) -> Identity a -> m Source #

ifoldr :: (() -> a -> b -> b) -> b -> Identity a -> b Source #

ifoldl :: (() -> b -> a -> b) -> b -> Identity a -> b Source #

ifoldr' :: (() -> a -> b -> b) -> b -> Identity a -> b Source #

ifoldl' :: (() -> b -> a -> b) -> b -> Identity a -> b Source #

TraversableWithIndex () Identity
Instance details

Defined in WithIndex

Methods

itraverse :: Applicative f => (() -> a -> f b) -> Identity a -> f ( Identity b) Source #

Sieve ReifiedGetter Identity Source #
Instance details

Defined in Control.Lens.Reified

Cosieve ReifiedGetter Identity Source #
Instance details

Defined in Control.Lens.Reified

Monad m => MonadFree Identity ( IterT m)
Instance details

Defined in Control.Monad.Trans.Iter

Comonad w => ComonadCofree Identity ( CoiterT w)
Instance details

Defined in Control.Comonad.Trans.Coiter

Unbox a => Vector Vector ( Identity a)
Instance details

Defined in Data.Vector.Unboxed.Base

Unbox a => MVector MVector ( Identity a)
Instance details

Defined in Data.Vector.Unboxed.Base

Bounded a => Bounded ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Enum a => Enum ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Eq a => Eq ( Identity a)

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Floating a => Floating ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Fractional a => Fractional ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Integral a => Integral ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Data a => Data ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Data

Methods

gfoldl :: ( forall d b. Data d => c (d -> b) -> d -> c b) -> ( forall g. g -> c g) -> Identity a -> c ( Identity a) Source #

gunfold :: ( forall b r. Data b => c (b -> r) -> c r) -> ( forall r. r -> c r) -> Constr -> c ( Identity a) Source #

toConstr :: Identity a -> Constr Source #

dataTypeOf :: Identity a -> DataType Source #

dataCast1 :: Typeable t => ( forall d. Data d => c (t d)) -> Maybe (c ( Identity a)) Source #

dataCast2 :: Typeable t => ( forall d e. ( Data d, Data e) => c (t d e)) -> Maybe (c ( Identity a)) Source #

gmapT :: ( forall b. Data b => b -> b) -> Identity a -> Identity a Source #

gmapQl :: (r -> r' -> r) -> r -> ( forall d. Data d => d -> r') -> Identity a -> r Source #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> ( forall d. Data d => d -> r') -> Identity a -> r Source #

gmapQ :: ( forall d. Data d => d -> u) -> Identity a -> [u] Source #

gmapQi :: Int -> ( forall d. Data d => d -> u) -> Identity a -> u Source #

gmapM :: Monad m => ( forall d. Data d => d -> m d) -> Identity a -> m ( Identity a) Source #

gmapMp :: MonadPlus m => ( forall d. Data d => d -> m d) -> Identity a -> m ( Identity a) Source #

gmapMo :: MonadPlus m => ( forall d. Data d => d -> m d) -> Identity a -> m ( Identity a) Source #

Num a => Num ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Ord a => Ord ( Identity a)

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Read a => Read ( Identity a)

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Real a => Real ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

RealFloat a => RealFloat ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

RealFrac a => RealFrac ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Show a => Show ( Identity a)

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Ix a => Ix ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Generic ( Identity a)

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Associated Types

type Rep ( Identity a) :: Type -> Type Source #

Semigroup a => Semigroup ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Monoid a => Monoid ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Storable a => Storable ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Bits a => Bits ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

FiniteBits a => FiniteBits ( Identity a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

NFData a => NFData ( Identity a)

Since: deepseq-1.4.0.0

Instance details

Defined in Control.DeepSeq

Hashable a => Hashable ( Identity a)
Instance details

Defined in Data.Hashable.Class

Prim a => Prim ( Identity a)

Since: primitive-0.6.5.0

Instance details

Defined in Data.Primitive.Types

Unbox a => Unbox ( Identity a)
Instance details

Defined in Data.Vector.Unboxed.Base

Wrapped ( Identity a) Source #
Instance details

Defined in Control.Lens.Wrapped

Associated Types

type Unwrapped ( Identity a) Source #

Ixed ( Identity a) Source #
Instance details

Defined in Control.Lens.At

Generic1 Identity

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Associated Types

type Rep1 Identity :: k -> Type Source #

t ~ Identity b => Rewrapped ( Identity a) t Source #
Instance details

Defined in Control.Lens.Wrapped

Field1 ( Identity a) ( Identity b) a b Source #
Instance details

Defined in Control.Lens.Tuple

Each ( Identity a) ( Identity b) a b Source #
each :: Traversal (Identity a) (Identity b) a b
Instance details

Defined in Control.Lens.Each

Sieve ((->) :: Type -> Type -> Type ) Identity
Instance details

Defined in Data.Profunctor.Sieve

Methods

sieve :: (a -> b) -> a -> Identity b Source #

Cosieve ((->) :: Type -> Type -> Type ) Identity
Instance details

Defined in Data.Profunctor.Sieve

Methods

cosieve :: (a -> b) -> Identity a -> b Source #

type Rep Identity
Instance details

Defined in Data.Functor.Rep

newtype MVector s ( Identity a)
Instance details

Defined in Data.Vector.Unboxed.Base

type Rep ( Identity a)
Instance details

Defined in Data.Functor.Identity

type Rep ( Identity a) = D1 (' MetaData "Identity" "Data.Functor.Identity" "base" ' True ) ( C1 (' MetaCons "Identity" ' PrefixI ' True ) ( S1 (' MetaSel (' Just "runIdentity") ' NoSourceUnpackedness ' NoSourceStrictness ' DecidedLazy ) ( Rec0 a)))
newtype Vector ( Identity a)
Instance details

Defined in Data.Vector.Unboxed.Base

type Unwrapped ( Identity a) Source #
Instance details

Defined in Control.Lens.Wrapped

type IxValue ( Identity a) Source #
Instance details

Defined in Control.Lens.At

type IxValue ( Identity a) = a
type Index ( Identity a) Source #
Instance details

Defined in Control.Lens.At

type Index ( Identity a) = ()
type Rep1 Identity
Instance details

Defined in Data.Functor.Identity

type Rep1 Identity = D1 (' MetaData "Identity" "Data.Functor.Identity" "base" ' True ) ( C1 (' MetaCons "Identity" ' PrefixI ' True ) ( S1 (' MetaSel (' Just "runIdentity") ' NoSourceUnpackedness ' NoSourceStrictness ' DecidedLazy ) Par1 ))

Deprecated

mapOf :: ASetter s t a b -> (a -> b) -> s -> t Source #

Deprecated: Use over

mapOf is a deprecated alias for over .