Copyright	(C) 2012-16 Edward Kmett
License	BSD-style (see the file LICENSE)
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	provisional
Portability	Rank2Types, TypeFamilies, FunctionalDependencies
Safe Haskell	Trustworthy
Language	Haskell2010

Control.Lens.Iso

Contents

Isomorphism Lenses
Isomorphism Construction
Consuming Isomorphisms
Working with isomorphisms
Profunctors
Bifunctors
Coercions

Description

Synopsis

type Iso s t a b = forall p f. (Profunctor p, Functor f) => p a (f b) -> p s (f t)
type Iso' s a = Iso s s a a
type AnIso s t a b = Exchange a b a (Identity b) -> Exchange a b s (Identity t)
type AnIso' s a = AnIso s s a a
iso :: (s -> a) -> (b -> t) -> Iso s t a b
from :: AnIso s t a b -> Iso b a t s
cloneIso :: AnIso s t a b -> Iso s t a b
withIso :: forall s t a b rep (r :: TYPE rep). AnIso s t a b -> ((s -> a) -> (b -> t) -> r) -> r
au :: Functor f => AnIso s t a b -> ((b -> t) -> f s) -> f a
auf :: (Functor f, Functor g) => AnIso s t a b -> (f t -> g s) -> f b -> g a
xplat :: Optic (Costar ((->) s)) g s t a b -> ((s -> a) -> g b) -> g t
xplatf :: Optic (Costar f) g s t a b -> (f a -> g b) -> f s -> g t
under :: AnIso s t a b -> (t -> s) -> b -> a
mapping :: (Functor f, Functor g) => AnIso s t a b -> Iso (f s) (g t) (f a) (g b)
simple :: Equality' a a
non :: Eq a => a -> Iso' (Maybe a) a
non' :: APrism' a () -> Iso' (Maybe a) a
anon :: a -> (a -> Bool) -> Iso' (Maybe a) a
enum :: Enum a => Iso' Int a
curried :: Iso ((a, b) -> c) ((d, e) -> f) (a -> b -> c) (d -> e -> f)
uncurried :: Iso (a -> b -> c) (d -> e -> f) ((a, b) -> c) ((d, e) -> f)
flipped :: Iso (a -> b -> c) (a' -> b' -> c') (b -> a -> c) (b' -> a' -> c')
class Bifunctor p => Swapped p where
- swapped :: Iso (p a b) (p c d) (p b a) (p d c)
pattern Swapped :: forall (p :: Type -> Type -> Type) c d. Swapped p => p d c -> p c d
class Strict lazy strict | lazy -> strict, strict -> lazy where
- strict :: Iso' lazy strict
pattern Strict :: forall s t. Strict s t => t -> s
pattern Lazy :: forall t s. Strict t s => t -> s
lazy :: Strict lazy strict => Iso' strict lazy
class Reversing t where
- reversing :: t -> t
reversed :: Reversing a => Iso' a a
pattern Reversed :: forall t. Reversing t => t -> t
involuted :: (a -> a) -> Iso' a a
pattern List :: forall l. IsList l => [Item l] -> l
magma :: LensLike (Mafic a b) s t a b -> Iso s u (Magma Int t b a) (Magma j u c c)
imagma :: Over (Indexed i) (Molten i a b) s t a b -> Iso s t' (Magma i t b a) (Magma j t' c c)
data Magma i t b a
contramapping :: Contravariant f => AnIso s t a b -> Iso (f a) (f b) (f s) (f t)
class Profunctor (p :: Type -> Type -> Type) where
- dimap :: (a -> b) -> (c -> d) -> p b c -> p a d
- lmap :: (a -> b) -> p b c -> p a c
- rmap :: (b -> c) -> p a b -> p a c
dimapping :: (Profunctor p, Profunctor q) => AnIso s t a b -> AnIso s' t' a' b' -> Iso (p a s') (q b t') (p s a') (q t b')
lmapping :: (Profunctor p, Profunctor q) => AnIso s t a b -> Iso (p a x) (q b y) (p s x) (q t y)
rmapping :: (Profunctor p, Profunctor q) => AnIso s t a b -> Iso (p x s) (q y t) (p x a) (q y b)
bimapping :: (Bifunctor f, Bifunctor g) => AnIso s t a b -> AnIso s' t' a' b' -> Iso (f s s') (g t t') (f a a') (g b b')
firsting :: (Bifunctor f, Bifunctor g) => AnIso s t a b -> Iso (f s x) (g t y) (f a x) (g b y)
seconding :: (Bifunctor f, Bifunctor g) => AnIso s t a b -> Iso (f x s) (g y t) (f x a) (g y b)
coerced :: forall s t a b. (Coercible s a, Coercible t b) => Iso s t a b

Isomorphism Lenses

type Iso s t a b = forall p f. (Profunctor p, Functor f) => p a (f b) -> p s (f t) Source #

Isomorphism families can be composed with another Lens using (.) and id.

Since every Iso is both a valid Lens and a valid Prism, the laws for those types imply the following laws for an Iso f:

f . from f ≡ id
from f . f ≡ id

Note: Composition with an Iso is index- and measure- preserving.

type Iso' s a = Iso s s a a Source #

type Iso' = Simple Iso

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

When you see this as an argument to a function, it expects an Iso.

type AnIso' s a = AnIso s s a a Source #

A Simple AnIso.

Isomorphism Construction

iso :: (s -> a) -> (b -> t) -> Iso s t a b Source #

Build a simple isomorphism from a pair of inverse functions.

view (iso f g) ≡ f
view (from (iso f g)) ≡ g
over (iso f g) h ≡ g . h . f
over (from (iso f g)) h ≡ f . h . g

Consuming Isomorphisms

from :: AnIso s t a b -> Iso b a t s Source #

Invert an isomorphism.

from (from l) ≡ l

cloneIso :: AnIso s t a b -> Iso s t a b Source #

Convert from AnIso back to any Iso.

This is useful when you need to store an isomorphism as a data type inside a container and later reconstitute it as an overloaded function.

See cloneLens or cloneTraversal for more information on why you might want to do this.

withIso :: forall s t a b rep (r :: TYPE rep). AnIso s t a b -> ((s -> a) -> (b -> t) -> r) -> r Source #

Extract the two functions, one from s -> a and one from b -> t that characterize an Iso.

Working with isomorphisms

au :: Functor f => AnIso s t a b -> ((b -> t) -> f s) -> f a Source #

Based on ala from Conor McBride's work on Epigram.

This version is generalized to accept any Iso, not just a newtype.

>>> au (_Wrapping Sum) foldMap [1,2,3,4]
10

You may want to think of this combinator as having the following, simpler type:

au :: AnIso s t a b -> ((b -> t) -> e -> s) -> e -> a

au = xplat . from

auf :: (Functor f, Functor g) => AnIso s t a b -> (f t -> g s) -> f b -> g a Source #

Based on ala' from Conor McBride's work on Epigram.

This version is generalized to accept any Iso, not just a newtype.

For a version you pass the name of the newtype constructor to, see alaf.

>>> auf (_Wrapping Sum) (foldMapOf both) Prelude.length ("hello","world")
10

Mnemonically, the German auf plays a similar role to à la, and the combinator is au with an extra function argument:

auf :: Iso s t a b -> ((r -> t) -> e -> s) -> (r -> b) -> e -> a

but the signature is general.

Note: The direction of the Iso required for this function changed in lens 4.18 to match up with the behavior of au. For the old behavior use xplatf or for a version that is compatible across both old and new versions of lens you can just use coerce!

xplat :: Optic (Costar ((->) s)) g s t a b -> ((s -> a) -> g b) -> g t Source #

xplat = au . from but with a nicer signature.

xplatf :: Optic (Costar f) g s t a b -> (f a -> g b) -> f s -> g t Source #

xplatf = auf . from but with a nicer signature.

>>> xplatf (_Unwrapping Sum) (foldMapOf both) Prelude.length ("hello","world")
10

xplatf :: Iso s t a b -> ((r -> a) -> e -> b) -> (r -> s) -> e -> t

under :: AnIso s t a b -> (t -> s) -> b -> a Source #

The opposite of working over a Setter is working under an isomorphism.

under ≡ over . from

under :: Iso s t a b -> (t -> s) -> b -> a

mapping :: (Functor f, Functor g) => AnIso s t a b -> Iso (f s) (g t) (f a) (g b) Source #

This can be used to lift any Iso into an arbitrary Functor.

Common Isomorphisms

simple :: Equality' a a Source #

Composition with this isomorphism is occasionally useful when your Lens, Traversal or Iso has a constraint on an unused argument to force that argument to agree with the type of a used argument and avoid ScopedTypeVariables or other ugliness.

non :: Eq a => a -> Iso' (Maybe a) a Source #

If v is an element of a type a, and a' is a sans the element v, then non v is an isomorphism from Maybe a' to a.

non ≡ non' . only

Keep in mind this is only a real isomorphism if you treat the domain as being Maybe (a sans v).

This is practically quite useful when you want to have a Map where all the entries should have non-zero values.

>>> Map.fromList [("hello",1)] & at "hello" . non 0 +~ 2
fromList [("hello",3)]

>>> Map.fromList [("hello",1)] & at "hello" . non 0 -~ 1
fromList []

>>> Map.fromList [("hello",1)] ^. at "hello" . non 0
1

>>> Map.fromList [] ^. at "hello" . non 0
0

This combinator is also particularly useful when working with nested maps.

e.g. When you want to create the nested Map when it is missing:

>>> Map.empty & at "hello" . non Map.empty . at "world" ?~ "!!!"
fromList [("hello",fromList [("world","!!!")])]

and when have deleting the last entry from the nested Map mean that we should delete its entry from the surrounding one:

>>> fromList [("hello",fromList [("world","!!!")])] & at "hello" . non Map.empty . at "world" .~ Nothing
fromList []

It can also be used in reverse to exclude a given value:

>>> non 0 # rem 10 4
Just 2

>>> non 0 # rem 10 5
Nothing

non' :: APrism' a () -> Iso' (Maybe a) a Source #

non' p generalizes non (p # ()) to take any unit Prism

This function generates an isomorphism between Maybe (a | isn't p a) and a.

>>> Map.singleton "hello" Map.empty & at "hello" . non' _Empty . at "world" ?~ "!!!"
fromList [("hello",fromList [("world","!!!")])]

>>> fromList [("hello",fromList [("world","!!!")])] & at "hello" . non' _Empty . at "world" .~ Nothing
fromList []

anon :: a -> (a -> Bool) -> Iso' (Maybe a) a Source #

anon a p generalizes non a to take any value and a predicate.

This function assumes that p a holds True and generates an isomorphism between Maybe (a | not (p a)) and a.

>>> Map.empty & at "hello" . anon Map.empty Map.null . at "world" ?~ "!!!"
fromList [("hello",fromList [("world","!!!")])]

>>> fromList [("hello",fromList [("world","!!!")])] & at "hello" . anon Map.empty Map.null . at "world" .~ Nothing
fromList []

enum :: Enum a => Iso' Int a Source #

This isomorphism can be used to convert to or from an instance of Enum.

>>> LT^.from enum
0

>>> 97^.enum :: Char
'a'

Note: this is only an isomorphism from the numeric range actually used and it is a bit of a pleasant fiction, since there are questionable Enum instances for Double, and Float that exist solely for [1.0 .. 4.0] sugar and the instances for those and Integer don't cover all values in their range.

curried :: Iso ((a, b) -> c) ((d, e) -> f) (a -> b -> c) (d -> e -> f) Source #

The canonical isomorphism for currying and uncurrying a function.

curried = iso curry uncurry

>>> (fst^.curried) 3 4
3

>>> view curried fst 3 4
3

uncurried :: Iso (a -> b -> c) (d -> e -> f) ((a, b) -> c) ((d, e) -> f) Source #

The canonical isomorphism for uncurrying and currying a function.

uncurried = iso uncurry curry

uncurried = from curried

>>> ((+)^.uncurried) (1,2)
3

flipped :: Iso (a -> b -> c) (a' -> b' -> c') (b -> a -> c) (b' -> a' -> c') Source #

The isomorphism for flipping a function.

>>> ((,)^.flipped) 1 2
(2,1)

class Bifunctor p => Swapped p where Source #

This class provides for symmetric bifunctors.

Methods

swapped :: Iso (p a b) (p c d) (p b a) (p d c) Source #

swapped . swapped ≡ id
first f . swapped = swapped . second f
second g . swapped = swapped . first g
bimap f g . swapped = swapped . bimap g f

>>> (1,2)^.swapped
(2,1)

Instances

Swapped Either Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (Either a b) (Either c d) (Either b a) (Either d c) Source #
Swapped (,) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (a, b) (c, d) (b, a) (d, c) Source #
Swapped ((,,) x) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (x, a, b) (x, c, d) (x, b, a) (x, d, c) Source #
Swapped ((,,,) x y) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (x, y, a, b) (x, y, c, d) (x, y, b, a) (x, y, d, c) Source #
Swapped ((,,,,) x y z) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (x, y, z, a, b) (x, y, z, c, d) (x, y, z, b, a) (x, y, z, d, c) Source #
Swapped p => Swapped (Flip p) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (Flip p a b) (Flip p c d) (Flip p b a) (Flip p d c) Source #
Swapped ((,,,,,) x y z w) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (x, y, z, w, a, b) (x, y, z, w, c, d) (x, y, z, w, b, a) (x, y, z, w, d, c) Source #
(Swapped p, Swapped q) => Swapped (Sum p q) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (Sum p q a b) (Sum p q c d) (Sum p q b a) (Sum p q d c) Source #
(Swapped f, Swapped g) => Swapped (Product f g) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (Product f g a b) (Product f g c d) (Product f g b a) (Product f g d c) Source #
Swapped ((,,,,,,) x y z w v) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (x, y, z, w, v, a, b) (x, y, z, w, v, c, d) (x, y, z, w, v, b, a) (x, y, z, w, v, d, c) Source #
(Functor f, Swapped p) => Swapped (Tannen f p) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (Tannen f p a b) (Tannen f p c d) (Tannen f p b a) (Tannen f p d c) Source #
(f ~ g, Functor f, Swapped p) => Swapped (Biff p f g) Source #
Instance details Defined in Control.Lens.Iso Methods swapped :: Iso (Biff p f g a b) (Biff p f g c d) (Biff p f g b a) (Biff p f g d c) Source #

pattern Swapped :: forall (p :: Type -> Type -> Type) c d. Swapped p => p d c -> p c d Source #

class Strict lazy strict | lazy -> strict, strict -> lazy where Source #

Ad hoc conversion between "strict" and "lazy" versions of a structure, such as Text or ByteString.

Methods

strict :: Iso' lazy strict Source #

Instances

Strict ByteString ByteString Source #
Instance details Defined in Control.Lens.Iso Methods strict :: Iso' ByteString0 ByteString Source #
Strict Text Text Source #
Instance details Defined in Control.Lens.Iso Methods strict :: Iso' Text0 Text Source #
Strict (ST s a) (ST s a) Source #
Instance details Defined in Control.Lens.Iso Methods strict :: Iso' (ST s a) (ST0 s a) Source #
Strict (StateT s m a) (StateT s m a) Source #
Instance details Defined in Control.Lens.Iso Methods strict :: Iso' (StateT0 s m a) (StateT s m a) Source #
Strict (WriterT w m a) (WriterT w m a) Source #
Instance details Defined in Control.Lens.Iso Methods strict :: Iso' (WriterT0 w m a) (WriterT w m a) Source #
Strict (RWST r w s m a) (RWST r w s m a) Source #
Instance details Defined in Control.Lens.Iso Methods strict :: Iso' (RWST0 r w s m a) (RWST r w s m a) Source #

pattern Strict :: forall s t. Strict s t => t -> s Source #

pattern Lazy :: forall t s. Strict t s => t -> s Source #

lazy :: Strict lazy strict => Iso' strict lazy Source #

An Iso between the strict variant of a structure and its lazy counterpart.

lazy = from strict

See http://hackage.haskell.org/package/strict-base-types for an example use.

class Reversing t where Source #

This class provides a generalized notion of list reversal extended to other containers.

Methods

reversing :: t -> t Source #

Instances

Reversing ByteString Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: ByteString -> ByteString Source #
Reversing ByteString Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: ByteString -> ByteString Source #
Reversing Text Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: Text -> Text Source #
Reversing Text Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: Text -> Text Source #
Reversing [a] Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: [a] -> [a] Source #
Reversing (NonEmpty a) Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: NonEmpty a -> NonEmpty a Source #
Reversing (Seq a) Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: Seq a -> Seq a Source #
Unbox a => Reversing (Vector a) Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: Vector a -> Vector a Source #
Storable a => Reversing (Vector a) Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: Vector a -> Vector a Source #
Prim a => Reversing (Vector a) Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: Vector a -> Vector a Source #
Reversing (Vector a) Source #
Instance details Defined in Control.Lens.Internal.Iso Methods reversing :: Vector a -> Vector a Source #
Reversing (Deque a) Source #
Instance details Defined in Control.Lens.Internal.Deque Methods reversing :: Deque a -> Deque a Source #

reversed :: Reversing a => Iso' a a Source #

An Iso between a list, ByteString, Text fragment, etc. and its reversal.

>>> "live" ^. reversed
"evil"

>>> "live" & reversed %~ ('d':)
"lived"

pattern Reversed :: forall t. Reversing t => t -> t Source #

involuted :: (a -> a) -> Iso' a a Source #

Given a function that is its own inverse, this gives you an Iso using it in both directions.

involuted ≡ join iso

>>> "live" ^. involuted reverse
"evil"

>>> "live" & involuted reverse %~ ('d':)
"lived"

pattern List :: forall l. IsList l => [Item l] -> l Source #

Uncommon Isomorphisms

magma :: LensLike (Mafic a b) s t a b -> Iso s u (Magma Int t b a) (Magma j u c c) Source #

This isomorphism can be used to inspect a Traversal to see how it associates the structure and it can also be used to bake the Traversal into a Magma so that you can traverse over it multiple times.

imagma :: Over (Indexed i) (Molten i a b) s t a b -> Iso s t' (Magma i t b a) (Magma j t' c c) Source #

This isomorphism can be used to inspect an IndexedTraversal to see how it associates the structure and it can also be used to bake the IndexedTraversal into a Magma so that you can traverse over it multiple times with access to the original indices.

data Magma i t b a Source #

This provides a way to peek at the internal structure of a Traversal or IndexedTraversal

Instances

TraversableWithIndex i (Magma i t b) Source #
Instance details Defined in Control.Lens.Indexed Methods itraverse :: Applicative f => (i -> a -> f b0) -> Magma i t b a -> f (Magma i t b b0) Source # itraversed :: IndexedTraversal i (Magma i t b a) (Magma i t b b0) a b0 Source #
FoldableWithIndex i (Magma i t b) Source #
Instance details Defined in Control.Lens.Indexed Methods ifoldMap :: Monoid m => (i -> a -> m) -> Magma i t b a -> m Source # ifolded :: IndexedFold i (Magma i t b a) a Source # ifoldr :: (i -> a -> b0 -> b0) -> b0 -> Magma i t b a -> b0 Source # ifoldl :: (i -> b0 -> a -> b0) -> b0 -> Magma i t b a -> b0 Source # ifoldr' :: (i -> a -> b0 -> b0) -> b0 -> Magma i t b a -> b0 Source # ifoldl' :: (i -> b0 -> a -> b0) -> b0 -> Magma i t b a -> b0 Source #
FunctorWithIndex i (Magma i t b) Source #
Instance details Defined in Control.Lens.Indexed Methods imap :: (i -> a -> b0) -> Magma i t b a -> Magma i t b b0 Source # imapped :: IndexedSetter i (Magma i t b a) (Magma i t b b0) a b0 Source #
Functor (Magma i t b) Source #
Instance details Defined in Control.Lens.Internal.Magma Methods fmap :: (a -> b0) -> Magma i t b a -> Magma i t b b0 # (<$) :: a -> Magma i t b b0 -> Magma i t b a #
Foldable (Magma i t b) Source #
Instance details Defined in Control.Lens.Internal.Magma Methods fold :: Monoid m => Magma i t b m -> m # foldMap :: Monoid m => (a -> m) -> Magma i t b a -> m # foldr :: (a -> b0 -> b0) -> b0 -> Magma i t b a -> b0 # foldr' :: (a -> b0 -> b0) -> b0 -> Magma i t b a -> b0 # foldl :: (b0 -> a -> b0) -> b0 -> Magma i t b a -> b0 # foldl' :: (b0 -> a -> b0) -> b0 -> Magma i t b a -> b0 # foldr1 :: (a -> a -> a) -> Magma i t b a -> a # foldl1 :: (a -> a -> a) -> Magma i t b a -> a # toList :: Magma i t b a -> [a] # null :: Magma i t b a -> Bool # length :: Magma i t b a -> Int # elem :: Eq a => a -> Magma i t b a -> Bool # maximum :: Ord a => Magma i t b a -> a # minimum :: Ord a => Magma i t b a -> a # sum :: Num a => Magma i t b a -> a # product :: Num a => Magma i t b a -> a #
Traversable (Magma i t b) Source #
Instance details Defined in Control.Lens.Internal.Magma Methods traverse :: Applicative f => (a -> f b0) -> Magma i t b a -> f (Magma i t b b0) # sequenceA :: Applicative f => Magma i t b (f a) -> f (Magma i t b a) # mapM :: Monad m => (a -> m b0) -> Magma i t b a -> m (Magma i t b b0) # sequence :: Monad m => Magma i t b (m a) -> m (Magma i t b a) #
(Show i, Show a) => Show (Magma i t b a) Source #
Instance details Defined in Control.Lens.Internal.Magma Methods showsPrec :: Int -> Magma i t b a -> ShowS # show :: Magma i t b a -> String # showList :: [Magma i t b a] -> ShowS #

Contravariant functors

contramapping :: Contravariant f => AnIso s t a b -> Iso (f a) (f b) (f s) (f t) Source #

Lift an Iso into a Contravariant functor.

contramapping :: Contravariant f => Iso s t a b -> Iso (f a) (f b) (f s) (f t)
contramapping :: Contravariant f => Iso' s a -> Iso' (f a) (f s)

Profunctors

class Profunctor (p :: Type -> Type -> Type) where #

Formally, the class Profunctor represents a profunctor from Hask -> Hask.

Intuitively it is a bifunctor where the first argument is contravariant and the second argument is covariant.

You can define a Profunctor by either defining dimap or by defining both lmap and rmap.

If you supply dimap, you should ensure that:

dimap id id ≡ id

If you supply lmap and rmap, ensure:

lmap id ≡ id
rmap id ≡ id

If you supply both, you should also ensure:

dimap f g ≡ lmap f . rmap g

These ensure by parametricity:

dimap (f . g) (h . i) ≡ dimap g h . dimap f i
lmap (f . g) ≡ lmap g . lmap f
rmap (f . g) ≡ rmap f . rmap g

Minimal complete definition

dimap | lmap, rmap

Methods

dimap :: (a -> b) -> (c -> d) -> p b c -> p a d #

Map over both arguments at the same time.

dimap f g ≡ lmap f . rmap g

lmap :: (a -> b) -> p b c -> p a c #

Map the first argument contravariantly.

lmap f ≡ dimap f id

rmap :: (b -> c) -> p a b -> p a c #

Map the second argument covariantly.

rmap ≡ dimap id

Instances

Profunctor ReifiedFold Source #
Instance details Defined in Control.Lens.Reified Methods dimap :: (a -> b) -> (c -> d) -> ReifiedFold b c -> ReifiedFold a d # lmap :: (a -> b) -> ReifiedFold b c -> ReifiedFold a c # rmap :: (b -> c) -> ReifiedFold a b -> ReifiedFold a c # (#.) :: Coercible c b => q b c -> ReifiedFold a b -> ReifiedFold a c # (.#) :: Coercible b a => ReifiedFold b c -> q a b -> ReifiedFold a c #
Profunctor ReifiedGetter Source #
Instance details Defined in Control.Lens.Reified Methods dimap :: (a -> b) -> (c -> d) -> ReifiedGetter b c -> ReifiedGetter a d # lmap :: (a -> b) -> ReifiedGetter b c -> ReifiedGetter a c # rmap :: (b -> c) -> ReifiedGetter a b -> ReifiedGetter a c # (#.) :: Coercible c b => q b c -> ReifiedGetter a b -> ReifiedGetter a c # (.#) :: Coercible b a => ReifiedGetter b c -> q a b -> ReifiedGetter a c #
Monad m => Profunctor (Kleisli m)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> Kleisli m b c -> Kleisli m a d # lmap :: (a -> b) -> Kleisli m b c -> Kleisli m a c # rmap :: (b -> c) -> Kleisli m a b -> Kleisli m a c # (#.) :: Coercible c b => q b c -> Kleisli m a b -> Kleisli m a c # (.#) :: Coercible b a => Kleisli m b c -> q a b -> Kleisli m a c #
Profunctor p => Profunctor (CofreeMapping p)
Instance details Defined in Data.Profunctor.Mapping Methods dimap :: (a -> b) -> (c -> d) -> CofreeMapping p b c -> CofreeMapping p a d # lmap :: (a -> b) -> CofreeMapping p b c -> CofreeMapping p a c # rmap :: (b -> c) -> CofreeMapping p a b -> CofreeMapping p a c # (#.) :: Coercible c b => q b c -> CofreeMapping p a b -> CofreeMapping p a c # (.#) :: Coercible b a => CofreeMapping p b c -> q a b -> CofreeMapping p a c #
Profunctor (FreeMapping p)
Instance details Defined in Data.Profunctor.Mapping Methods dimap :: (a -> b) -> (c -> d) -> FreeMapping p b c -> FreeMapping p a d # lmap :: (a -> b) -> FreeMapping p b c -> FreeMapping p a c # rmap :: (b -> c) -> FreeMapping p a b -> FreeMapping p a c # (#.) :: Coercible c b => q b c -> FreeMapping p a b -> FreeMapping p a c # (.#) :: Coercible b a => FreeMapping p b c -> q a b -> FreeMapping p a c #
Profunctor p => Profunctor (TambaraSum p)
Instance details Defined in Data.Profunctor.Choice Methods dimap :: (a -> b) -> (c -> d) -> TambaraSum p b c -> TambaraSum p a d # lmap :: (a -> b) -> TambaraSum p b c -> TambaraSum p a c # rmap :: (b -> c) -> TambaraSum p a b -> TambaraSum p a c # (#.) :: Coercible c b => q b c -> TambaraSum p a b -> TambaraSum p a c # (.#) :: Coercible b a => TambaraSum p b c -> q a b -> TambaraSum p a c #
Profunctor (PastroSum p)
Instance details Defined in Data.Profunctor.Choice Methods dimap :: (a -> b) -> (c -> d) -> PastroSum p b c -> PastroSum p a d # lmap :: (a -> b) -> PastroSum p b c -> PastroSum p a c # rmap :: (b -> c) -> PastroSum p a b -> PastroSum p a c # (#.) :: Coercible c b => q b c -> PastroSum p a b -> PastroSum p a c # (.#) :: Coercible b a => PastroSum p b c -> q a b -> PastroSum p a c #
Profunctor (CotambaraSum p)
Instance details Defined in Data.Profunctor.Choice Methods dimap :: (a -> b) -> (c -> d) -> CotambaraSum p b c -> CotambaraSum p a d # lmap :: (a -> b) -> CotambaraSum p b c -> CotambaraSum p a c # rmap :: (b -> c) -> CotambaraSum p a b -> CotambaraSum p a c # (#.) :: Coercible c b => q b c -> CotambaraSum p a b -> CotambaraSum p a c # (.#) :: Coercible b a => CotambaraSum p b c -> q a b -> CotambaraSum p a c #
Profunctor (CopastroSum p)
Instance details Defined in Data.Profunctor.Choice Methods dimap :: (a -> b) -> (c -> d) -> CopastroSum p b c -> CopastroSum p a d # lmap :: (a -> b) -> CopastroSum p b c -> CopastroSum p a c # rmap :: (b -> c) -> CopastroSum p a b -> CopastroSum p a c # (#.) :: Coercible c b => q b c -> CopastroSum p a b -> CopastroSum p a c # (.#) :: Coercible b a => CopastroSum p b c -> q a b -> CopastroSum p a c #
Profunctor p => Profunctor (Closure p)
Instance details Defined in Data.Profunctor.Closed Methods dimap :: (a -> b) -> (c -> d) -> Closure p b c -> Closure p a d # lmap :: (a -> b) -> Closure p b c -> Closure p a c # rmap :: (b -> c) -> Closure p a b -> Closure p a c # (#.) :: Coercible c b => q b c -> Closure p a b -> Closure p a c # (.#) :: Coercible b a => Closure p b c -> q a b -> Closure p a c #
Profunctor (Environment p)
Instance details Defined in Data.Profunctor.Closed Methods dimap :: (a -> b) -> (c -> d) -> Environment p b c -> Environment p a d # lmap :: (a -> b) -> Environment p b c -> Environment p a c # rmap :: (b -> c) -> Environment p a b -> Environment p a c # (#.) :: Coercible c b => q b c -> Environment p a b -> Environment p a c # (.#) :: Coercible b a => Environment p b c -> q a b -> Environment p a c #
Profunctor p => Profunctor (Tambara p)
Instance details Defined in Data.Profunctor.Strong Methods dimap :: (a -> b) -> (c -> d) -> Tambara p b c -> Tambara p a d # lmap :: (a -> b) -> Tambara p b c -> Tambara p a c # rmap :: (b -> c) -> Tambara p a b -> Tambara p a c # (#.) :: Coercible c b => q b c -> Tambara p a b -> Tambara p a c # (.#) :: Coercible b a => Tambara p b c -> q a b -> Tambara p a c #
Profunctor (Pastro p)
Instance details Defined in Data.Profunctor.Strong Methods dimap :: (a -> b) -> (c -> d) -> Pastro p b c -> Pastro p a d # lmap :: (a -> b) -> Pastro p b c -> Pastro p a c # rmap :: (b -> c) -> Pastro p a b -> Pastro p a c # (#.) :: Coercible c b => q b c -> Pastro p a b -> Pastro p a c # (.#) :: Coercible b a => Pastro p b c -> q a b -> Pastro p a c #
Profunctor (Cotambara p)
Instance details Defined in Data.Profunctor.Strong Methods dimap :: (a -> b) -> (c -> d) -> Cotambara p b c -> Cotambara p a d # lmap :: (a -> b) -> Cotambara p b c -> Cotambara p a c # rmap :: (b -> c) -> Cotambara p a b -> Cotambara p a c # (#.) :: Coercible c b => q b c -> Cotambara p a b -> Cotambara p a c # (.#) :: Coercible b a => Cotambara p b c -> q a b -> Cotambara p a c #
Profunctor (Copastro p)
Instance details Defined in Data.Profunctor.Strong Methods dimap :: (a -> b) -> (c -> d) -> Copastro p b c -> Copastro p a d # lmap :: (a -> b) -> Copastro p b c -> Copastro p a c # rmap :: (b -> c) -> Copastro p a b -> Copastro p a c # (#.) :: Coercible c b => q b c -> Copastro p a b -> Copastro p a c # (.#) :: Coercible b a => Copastro p b c -> q a b -> Copastro p a c #
Functor f => Profunctor (Star f)
Instance details Defined in Data.Profunctor.Types Methods dimap :: (a -> b) -> (c -> d) -> Star f b c -> Star f a d # lmap :: (a -> b) -> Star f b c -> Star f a c # rmap :: (b -> c) -> Star f a b -> Star f a c # (#.) :: Coercible c b => q b c -> Star f a b -> Star f a c # (.#) :: Coercible b a => Star f b c -> q a b -> Star f a c #
Functor f => Profunctor (Costar f)
Instance details Defined in Data.Profunctor.Types Methods dimap :: (a -> b) -> (c -> d) -> Costar f b c -> Costar f a d # lmap :: (a -> b) -> Costar f b c -> Costar f a c # rmap :: (b -> c) -> Costar f a b -> Costar f a c # (#.) :: Coercible c b => q b c -> Costar f a b -> Costar f a c # (.#) :: Coercible b a => Costar f b c -> q a b -> Costar f a c #
Arrow p => Profunctor (WrappedArrow p)
Instance details Defined in Data.Profunctor.Types Methods dimap :: (a -> b) -> (c -> d) -> WrappedArrow p b c -> WrappedArrow p a d # lmap :: (a -> b) -> WrappedArrow p b c -> WrappedArrow p a c # rmap :: (b -> c) -> WrappedArrow p a b -> WrappedArrow p a c # (#.) :: Coercible c b => q b c -> WrappedArrow p a b -> WrappedArrow p a c # (.#) :: Coercible b a => WrappedArrow p b c -> q a b -> WrappedArrow p a c #
Profunctor (Forget r)
Instance details Defined in Data.Profunctor.Types Methods dimap :: (a -> b) -> (c -> d) -> Forget r b c -> Forget r a d # lmap :: (a -> b) -> Forget r b c -> Forget r a c # rmap :: (b -> c) -> Forget r a b -> Forget r a c # (#.) :: Coercible c b => q b c -> Forget r a b -> Forget r a c # (.#) :: Coercible b a => Forget r b c -> q a b -> Forget r a c #
Profunctor (Tagged :: Type -> Type -> Type)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> Tagged b c -> Tagged a d # lmap :: (a -> b) -> Tagged b c -> Tagged a c # rmap :: (b -> c) -> Tagged a b -> Tagged a c # (#.) :: Coercible c b => q b c -> Tagged a b -> Tagged a c # (.#) :: Coercible b a => Tagged b c -> q a b -> Tagged a c #
Profunctor (Indexed i) Source #
Instance details Defined in Control.Lens.Internal.Indexed Methods dimap :: (a -> b) -> (c -> d) -> Indexed i b c -> Indexed i a d # lmap :: (a -> b) -> Indexed i b c -> Indexed i a c # rmap :: (b -> c) -> Indexed i a b -> Indexed i a c # (#.) :: Coercible c b => q b c -> Indexed i a b -> Indexed i a c # (.#) :: Coercible b a => Indexed i b c -> q a b -> Indexed i a c #
Profunctor (ReifiedIndexedFold i) Source #
Instance details Defined in Control.Lens.Reified Methods dimap :: (a -> b) -> (c -> d) -> ReifiedIndexedFold i b c -> ReifiedIndexedFold i a d # lmap :: (a -> b) -> ReifiedIndexedFold i b c -> ReifiedIndexedFold i a c # rmap :: (b -> c) -> ReifiedIndexedFold i a b -> ReifiedIndexedFold i a c # (#.) :: Coercible c b => q b c -> ReifiedIndexedFold i a b -> ReifiedIndexedFold i a c # (.#) :: Coercible b a => ReifiedIndexedFold i b c -> q a b -> ReifiedIndexedFold i a c #
Profunctor (ReifiedIndexedGetter i) Source #
Instance details Defined in Control.Lens.Reified Methods dimap :: (a -> b) -> (c -> d) -> ReifiedIndexedGetter i b c -> ReifiedIndexedGetter i a d # lmap :: (a -> b) -> ReifiedIndexedGetter i b c -> ReifiedIndexedGetter i a c # rmap :: (b -> c) -> ReifiedIndexedGetter i a b -> ReifiedIndexedGetter i a c # (#.) :: Coercible c b => q b c -> ReifiedIndexedGetter i a b -> ReifiedIndexedGetter i a c # (.#) :: Coercible b a => ReifiedIndexedGetter i b c -> q a b -> ReifiedIndexedGetter i a c #
Profunctor ((->) :: Type -> Type -> Type)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> (b -> c) -> a -> d # lmap :: (a -> b) -> (b -> c) -> a -> c # rmap :: (b -> c) -> (a -> b) -> a -> c # (#.) :: Coercible c b => q b c -> (a -> b) -> a -> c # (.#) :: Coercible b a => (b -> c) -> q a b -> a -> c #
Functor w => Profunctor (Cokleisli w)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> Cokleisli w b c -> Cokleisli w a d # lmap :: (a -> b) -> Cokleisli w b c -> Cokleisli w a c # rmap :: (b -> c) -> Cokleisli w a b -> Cokleisli w a c # (#.) :: Coercible c b => q b c -> Cokleisli w a b -> Cokleisli w a c # (.#) :: Coercible b a => Cokleisli w b c -> q a b -> Cokleisli w a c #
(Functor f, Profunctor p) => Profunctor (Cayley f p)
Instance details Defined in Data.Profunctor.Cayley Methods dimap :: (a -> b) -> (c -> d) -> Cayley f p b c -> Cayley f p a d # lmap :: (a -> b) -> Cayley f p b c -> Cayley f p a c # rmap :: (b -> c) -> Cayley f p a b -> Cayley f p a c # (#.) :: Coercible c b => q b c -> Cayley f p a b -> Cayley f p a c # (.#) :: Coercible b a => Cayley f p b c -> q a b -> Cayley f p a c #
(Profunctor p, Profunctor q) => Profunctor (Procompose p q)
Instance details Defined in Data.Profunctor.Composition Methods dimap :: (a -> b) -> (c -> d) -> Procompose p q b c -> Procompose p q a d # lmap :: (a -> b) -> Procompose p q b c -> Procompose p q a c # rmap :: (b -> c) -> Procompose p q a b -> Procompose p q a c # (#.) :: Coercible c b => q0 b c -> Procompose p q a b -> Procompose p q a c # (.#) :: Coercible b a => Procompose p q b c -> q0 a b -> Procompose p q a c #
(Profunctor p, Profunctor q) => Profunctor (Rift p q)
Instance details Defined in Data.Profunctor.Composition Methods dimap :: (a -> b) -> (c -> d) -> Rift p q b c -> Rift p q a d # lmap :: (a -> b) -> Rift p q b c -> Rift p q a c # rmap :: (b -> c) -> Rift p q a b -> Rift p q a c # (#.) :: Coercible c b => q0 b c -> Rift p q a b -> Rift p q a c # (.#) :: Coercible b a => Rift p q b c -> q0 a b -> Rift p q a c #
Profunctor (Exchange a b) Source #
Instance details Defined in Control.Lens.Internal.Iso Methods dimap :: (a0 -> b0) -> (c -> d) -> Exchange a b b0 c -> Exchange a b a0 d # lmap :: (a0 -> b0) -> Exchange a b b0 c -> Exchange a b a0 c # rmap :: (b0 -> c) -> Exchange a b a0 b0 -> Exchange a b a0 c # (#.) :: Coercible c b0 => q b0 c -> Exchange a b a0 b0 -> Exchange a b a0 c # (.#) :: Coercible b0 a0 => Exchange a b b0 c -> q a0 b0 -> Exchange a b a0 c #
Profunctor (Market a b) Source #
Instance details Defined in Control.Lens.Internal.Prism Methods dimap :: (a0 -> b0) -> (c -> d) -> Market a b b0 c -> Market a b a0 d # lmap :: (a0 -> b0) -> Market a b b0 c -> Market a b a0 c # rmap :: (b0 -> c) -> Market a b a0 b0 -> Market a b a0 c # (#.) :: Coercible c b0 => q b0 c -> Market a b a0 b0 -> Market a b a0 c # (.#) :: Coercible b0 a0 => Market a b b0 c -> q a0 b0 -> Market a b a0 c #
Functor f => Profunctor (Joker f :: Type -> Type -> Type)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> Joker f b c -> Joker f a d # lmap :: (a -> b) -> Joker f b c -> Joker f a c # rmap :: (b -> c) -> Joker f a b -> Joker f a c # (#.) :: Coercible c b => q b c -> Joker f a b -> Joker f a c # (.#) :: Coercible b a => Joker f b c -> q a b -> Joker f a c #
Contravariant f => Profunctor (Clown f :: Type -> Type -> Type)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> Clown f b c -> Clown f a d # lmap :: (a -> b) -> Clown f b c -> Clown f a c # rmap :: (b -> c) -> Clown f a b -> Clown f a c # (#.) :: Coercible c b => q b c -> Clown f a b -> Clown f a c # (.#) :: Coercible b a => Clown f b c -> q a b -> Clown f a c #
(Profunctor p, Profunctor q) => Profunctor (Sum p q)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> Sum p q b c -> Sum p q a d # lmap :: (a -> b) -> Sum p q b c -> Sum p q a c # rmap :: (b -> c) -> Sum p q a b -> Sum p q a c # (#.) :: Coercible c b => q0 b c -> Sum p q a b -> Sum p q a c # (.#) :: Coercible b a => Sum p q b c -> q0 a b -> Sum p q a c #
(Profunctor p, Profunctor q) => Profunctor (Product p q)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> Product p q b c -> Product p q a d # lmap :: (a -> b) -> Product p q b c -> Product p q a c # rmap :: (b -> c) -> Product p q a b -> Product p q a c # (#.) :: Coercible c b => q0 b c -> Product p q a b -> Product p q a c # (.#) :: Coercible b a => Product p q b c -> q0 a b -> Product p q a c #
(Functor f, Profunctor p) => Profunctor (Tannen f p)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> Tannen f p b c -> Tannen f p a d # lmap :: (a -> b) -> Tannen f p b c -> Tannen f p a c # rmap :: (b -> c) -> Tannen f p a b -> Tannen f p a c # (#.) :: Coercible c b => q b c -> Tannen f p a b -> Tannen f p a c # (.#) :: Coercible b a => Tannen f p b c -> q a b -> Tannen f p a c #
(Profunctor p, Functor f, Functor g) => Profunctor (Biff p f g)
Instance details Defined in Data.Profunctor.Unsafe Methods dimap :: (a -> b) -> (c -> d) -> Biff p f g b c -> Biff p f g a d # lmap :: (a -> b) -> Biff p f g b c -> Biff p f g a c # rmap :: (b -> c) -> Biff p f g a b -> Biff p f g a c # (#.) :: Coercible c b => q b c -> Biff p f g a b -> Biff p f g a c # (.#) :: Coercible b a => Biff p f g b c -> q a b -> Biff p f g a c #

dimapping :: (Profunctor p, Profunctor q) => AnIso s t a b -> AnIso s' t' a' b' -> Iso (p a s') (q b t') (p s a') (q t b') Source #

Lift two Isos into both arguments of a Profunctor simultaneously.

dimapping :: Profunctor p => Iso s t a b -> Iso s' t' a' b' -> Iso (p a s') (p b t') (p s a') (p t b')
dimapping :: Profunctor p => Iso' s a -> Iso' s' a' -> Iso' (p a s') (p s a')

lmapping :: (Profunctor p, Profunctor q) => AnIso s t a b -> Iso (p a x) (q b y) (p s x) (q t y) Source #

Lift an Iso contravariantly into the left argument of a Profunctor.

lmapping :: Profunctor p => Iso s t a b -> Iso (p a x) (p b y) (p s x) (p t y)
lmapping :: Profunctor p => Iso' s a -> Iso' (p a x) (p s x)

rmapping :: (Profunctor p, Profunctor q) => AnIso s t a b -> Iso (p x s) (q y t) (p x a) (q y b) Source #

Lift an Iso covariantly into the right argument of a Profunctor.

rmapping :: Profunctor p => Iso s t a b -> Iso (p x s) (p y t) (p x a) (p y b)
rmapping :: Profunctor p => Iso' s a -> Iso' (p x s) (p x a)

Bifunctors

bimapping :: (Bifunctor f, Bifunctor g) => AnIso s t a b -> AnIso s' t' a' b' -> Iso (f s s') (g t t') (f a a') (g b b') Source #

Lift two Isos into both arguments of a Bifunctor.

bimapping :: Bifunctor p => Iso s t a b -> Iso s' t' a' b' -> Iso (p s s') (p t t') (p a a') (p b b')
bimapping :: Bifunctor p => Iso' s a -> Iso' s' a' -> Iso' (p s s') (p a a')

firsting :: (Bifunctor f, Bifunctor g) => AnIso s t a b -> Iso (f s x) (g t y) (f a x) (g b y) Source #

Lift an Iso into the first argument of a Bifunctor.

firsting :: Bifunctor p => Iso s t a b -> Iso (p s x) (p t y) (p a x) (p b y)
firsting :: Bifunctor p => Iso' s a -> Iso' (p s x) (p a x)

seconding :: (Bifunctor f, Bifunctor g) => AnIso s t a b -> Iso (f x s) (g y t) (f x a) (g y b) Source #

Lift an Iso into the second argument of a Bifunctor. This is essentially the same as mapping, but it takes a 'Bifunctor p' constraint instead of a 'Functor (p a)' one.

seconding :: Bifunctor p => Iso s t a b -> Iso (p x s) (p y t) (p x a) (p y b)
seconding :: Bifunctor p => Iso' s a -> Iso' (p x s) (p x a)

Coercions

coerced :: forall s t a b. (Coercible s a, Coercible t b) => Iso s t a b Source #

Data types that are representationally equal are isomorphic.

This is only available on GHC 7.8+

Since: 4.13