Optics.IxLens

An IxLens is an indexed version of a Lens. See the "Indexed optics" section of the overview documentation in the Optics module of the main optics package for more details on indexed optics.

Formation

type IxLens i s t a b = Optic A_Lens (WithIx i) s t a b

Type synonym for a type-modifying indexed lens.

type IxLens' i s a = Optic' A_Lens (WithIx i) s a

Type synonym for a type-preserving indexed lens.

Introduction

ilens :: (s -> (i, a)) -> (s -> b -> t) -> IxLens i s t a b

Build an indexed lens from a getter and a setter.

If you want to build an IxLens from the van Laarhoven representation, use ilensVL.

Elimination

An IxLens is in particular an IxGetter and an IxSetter, therefore you can specialise types to obtain:

iview :: IxLens i s t a b -> s -> (i, a)

iover :: IxLens i s t a b -> (i -> a -> b) -> s -> t
iset  :: IxLens i s t a b -> (i      -> b) -> s -> t

Additional introduction forms

devoid :: IxLens' i Void a

There is an indexed field for every type in the Void.

>>> set (mapped % devoid) 1 []
[]

>>> over (_Just % devoid) abs Nothing
Nothing

Subtyping

data A_Lens :: OpticKind

Tag for a lens.

Instances

ReversibleOptic A_Lens

Defined in Optics.Re

Associated Types

type ReversedOptic A_Lens = (r :: Type)

Methods

re :: AcceptsEmptyIndices "re" is => Optic A_Lens is s t a b -> Optic (ReversedOptic A_Lens) is b a t s

Is A_Lens A_Fold

Defined in Optics.Internal.Optic.Subtyping

Methods

implies :: (Constraints A_Lens p -> r) -> Constraints A_Fold p -> r

Is A_Lens An_AffineFold

Defined in Optics.Internal.Optic.Subtyping

Methods

implies :: (Constraints A_Lens p -> r) -> Constraints An_AffineFold p -> r

Is A_Lens A_Getter

Defined in Optics.Internal.Optic.Subtyping

Methods

implies :: (Constraints A_Lens p -> r) -> Constraints A_Getter p -> r

Is A_Lens A_Setter

Defined in Optics.Internal.Optic.Subtyping

Methods

implies :: (Constraints A_Lens p -> r) -> Constraints A_Setter p -> r

Is A_Lens A_Traversal

Defined in Optics.Internal.Optic.Subtyping

Methods

implies :: (Constraints A_Lens p -> r) -> Constraints A_Traversal p -> r

Is A_Lens An_AffineTraversal

Defined in Optics.Internal.Optic.Subtyping

Methods

implies :: (Constraints A_Lens p -> r) -> Constraints An_AffineTraversal p -> r

Is An_Iso A_Lens

Defined in Optics.Internal.Optic.Subtyping

Methods

implies :: (Constraints An_Iso p -> r) -> Constraints A_Lens p -> r

Arrow arr => ArrowOptic A_Lens arr

Defined in Optics.Arrow

Methods

overA :: Optic A_Lens is s t a b -> arr a b -> arr s t

ToReadOnly A_Lens s t a b

Defined in Optics.ReadOnly

Methods

getting :: Optic A_Lens is s t a b -> Optic' (Join A_Getter A_Lens) is s a

IxOptic A_Lens s t a b

Defined in Optics.Indexed.Core

Methods

noIx :: NonEmptyIndices is => Optic A_Lens is s t a b -> Optic A_Lens NoIx s t a b

(Functor f, f ~ g, s ~ t, a ~ b) => MappingOptic A_Lens f g s t a b

Defined in Optics.Mapping

Associated Types

type MappedOptic A_Lens :: Type

Methods

mapping :: AcceptsEmptyIndices "mapping" is => Optic A_Lens is s t a b -> Optic (MappedOptic A_Lens) is (f s) (g t) (f a) (g b)

type ReversedOptic A_Lens

Defined in Optics.Re

type ReversedOptic A_Lens = A_ReversedLens

type MappedOptic A_Lens

Defined in Optics.Mapping

type MappedOptic A_Lens = A_Getter

van Laarhoven encoding

type IxLensVL i s t a b = forall f. Functor f => (i -> a -> f b) -> s -> f t

Type synonym for a type-modifying van Laarhoven indexed lens.

type IxLensVL' i s a = IxLensVL i s s a a

Type synonym for a type-preserving van Laarhoven indexed lens.

ilensVL :: IxLensVL i s t a b -> IxLens i s t a b

Build an indexed lens from the van Laarhoven representation.

toIxLensVL :: (Is k A_Lens, is `HasSingleIndex` i) => Optic k is s t a b -> IxLensVL i s t a b

Convert an indexed lens to its van Laarhoven representation.

withIxLensVL :: (Is k A_Lens, is `HasSingleIndex` i) => Optic k is s t a b -> (IxLensVL i s t a b -> r) -> r

Work with an indexed lens in the van Laarhoven representation.