| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Optics.IxAffineFold
Description
An IxAffineFold is an indexed version of an AffineFold.
See the "Indexed optics" section of the overview documentation in the
Optics module of the main optics package for more details on indexed
optics.
Synopsis
- type IxAffineFold i s a = Optic' An_AffineFold (WithIx i) s a
- iafolding :: (s -> Maybe (i, a)) -> IxAffineFold i s a
- ipreview :: (Is k An_AffineFold, is `HasSingleIndex` i) => Optic' k is s a -> s -> Maybe (i, a)
- ipreviews :: (Is k An_AffineFold, is `HasSingleIndex` i) => Optic' k is s a -> (i -> a -> r) -> s -> Maybe r
- iafoldVL :: (forall f. Functor f => (forall r. r -> f r) -> (i -> a -> f u) -> s -> f v) -> IxAffineFold i s a
- iatraverseOf_ :: (Is k An_AffineFold, Functor f, is `HasSingleIndex` i) => Optic' k is s a -> (forall r. r -> f r) -> (i -> a -> f u) -> s -> f ()
- filteredBy :: Is k An_AffineFold => Optic' k is a i -> IxAffineFold i a a
- iafailing :: (Is k An_AffineFold, Is l An_AffineFold, is1 `HasSingleIndex` i, is2 `HasSingleIndex` i) => Optic' k is1 s a -> Optic' l is2 s a -> IxAffineFold i s a
- data An_AffineFold :: OpticKind
Formation
type IxAffineFold i s a = Optic' An_AffineFold (WithIx i) s a Source #
Type synonym for an indexed affine fold.
Introduction
iafolding :: (s -> Maybe (i, a)) -> IxAffineFold i s a Source #
Create an IxAffineFold from a partial function.
Elimination
ipreview :: (Is k An_AffineFold, is `HasSingleIndex` i) => Optic' k is s a -> s -> Maybe (i, a) Source #
Retrieve the value along with its index targeted by an IxAffineFold.
ipreviews :: (Is k An_AffineFold, is `HasSingleIndex` i) => Optic' k is s a -> (i -> a -> r) -> s -> Maybe r Source #
Retrieve a function of the value and its index targeted by an
IxAffineFold.
Computation
Additional introduction forms
iafoldVL :: (forall f. Functor f => (forall r. r -> f r) -> (i -> a -> f u) -> s -> f v) -> IxAffineFold i s a Source #
Obtain an IxAffineFold by lifting itraverse_ like function.
aifoldVL.iatraverseOf_≡idaitraverseOf_.iafoldVL≡id
Since: 0.3
Additional elimination forms
iatraverseOf_ :: (Is k An_AffineFold, Functor f, is `HasSingleIndex` i) => Optic' k is s a -> (forall r. r -> f r) -> (i -> a -> f u) -> s -> f () Source #
Traverse over the target of an IxAffineFold, computing a Functor-based
answer, but unlike iatraverseOf do not construct a
new structure.
Since: 0.3
Combinators
filteredBy :: Is k An_AffineFold => Optic' k is a i -> IxAffineFold i a a Source #
Obtain a potentially empty IxAffineFold by taking the element from
another AffineFold and using it as an index.
Since: 0.3
Monoid structure
IxAffineFold admits a monoid structure where iafailing combines folds
(returning a result from the second fold only if the first returns none)
and the identity element is ignored (which
returns no results).
Note: There is no isumming equivalent that returns an
IxAffineFold, because it would not need to return more than one result.
There is no Semigroup or Monoid instance for IxAffineFold, because
there is not a unique choice of monoid to use that works for all optics,
and the (<>) operator could not be used to combine optics of different
kinds.
iafailing :: (Is k An_AffineFold, Is l An_AffineFold, is1 `HasSingleIndex` i, is2 `HasSingleIndex` i) => Optic' k is1 s a -> Optic' l is2 s a -> IxAffineFold i s a infixl 3 Source #
Try the first IxAffineFold. If it returns no entry, try the second one.
Subtyping
data An_AffineFold :: OpticKind Source #
Tag for an affine fold.