//arrow-optics/arrow.optics/PLens

PLens

common interface PLens<S, T, A, B> : Getter<S, A> , POptional<S, T, A, B> , PSetter<S, T, A, B> , Fold<S, A> , PTraversal<S, T, A, B> , PEvery<S, T, A, B>

A Lens (or Functional Reference) is an optic that can focus into a structure for getting, setting or modifying the focus (target).

A (polymorphic) PLens is useful when setting or modifying a value for a constructed type i.e. PLens, Pair, Double, String>

A PLens can be seen as a pair of functions:

  • get: (S) -> A meaning we can focus into an S and extract an A
  • set: (B) -> (S) -> T meaning we can focus into an S and set a value B for a target A and obtain a modified source T

Parameters

common

   
S the source of a PLens
T the modified source of a PLens
A the focus of a PLens
B the modified focus of a PLens

Types

Name Summary
Companion common object Companion

Functions

Name Summary
all common open fun all(source: S, predicate: (A) -> Boolean): Boolean
Check if all targets satisfy the predicate
any common open fun any(source: S, predicate: (A) -> Boolean): Boolean
Returns true if at least one focus matches the given predicate.
choice common open infix fun <C> choice(other: Fold<C, A>): Fold<Either<S, C>, A>
Join two Fold with the same target
common open infix fun <C> choice(other: Getter<C, A>): Getter<Either<S, C>, A>
Join two Getter with the same focus
common open infix fun <S1, T1> choice(other: PLens<S1, T1, A, B>): PLens<Either<S, S1>, Either<T, T1>, A, B>
Join two PLens with the same focus in A
common open infix fun <S1, T1> choice(other: POptional<S1, T1, A, B>): POptional<Either<S, S1>, Either<T, T1>, A, B>
Join two POptional with the same focus B
common open infix fun <U, V> choice(other: PSetter<U, V, A, B>): PSetter<Either<S, U>, Either<T, V>, A, B>
Join two PSetter with the same target
common open fun <U, V> choice(other: PTraversal<U, V, A, B>): PTraversal<Either<S, U>, Either<T, V>, A, B>
combineAll common open fun combineAll(M: Monoid<A>, source: S): A
Alias for fold.
compose common open infix fun <C> compose(other: Fold<in A, out C>): Fold<S, C>
Compose a Fold with a Fold
common open infix fun <C> compose(other: Getter<in A, out C>): Getter<S, C>
Compose a Getter with a Getter
common open infix fun <C, D> compose(other: PEvery<in A, out B, out C, in D>): PEvery<S, T, C, D>
Compose a PEvery with a PEvery
common open infix fun <C, D> compose(other: PLens<in A, out B, out C, in D>): PLens<S, T, C, D>
Compose a PLens with another PLens
common open infix fun <C, D> compose(other: POptional<in A, out B, out C, in D>): POptional<S, T, C, D>
Compose a POptional with a POptional
common open infix fun <C, D> compose(other: PSetter<in A, out B, out C, in D>): PSetter<S, T, C, D>
Compose a PSetter with a PSetter
common open infix fun <C, D> compose(other: PTraversal<in A, out B, out C, in D>): PTraversal<S, T, C, D>
Compose a PTraversal with a PTraversal
exists common open fun exists(source: S, predicate: (A) -> Boolean): Boolean
Check whether at least one element satisfies the predicate.
findOrNull common open fun findOrNull(source: S, predicate: (A) -> Boolean): A?
Find the first element matching the predicate, if one exists.
first common open override fun <C> first(): PLens<Pair<S, C>, Pair<T, C>, Pair<A, C>, Pair<B, C»
Create a product of the PLens and a type C
firstOrNull common open fun firstOrNull(source: S): A?
Get the first target or null
fold common open fun fold(M: Monoid<A>, source: S): A
Fold using the given Monoid instance.
foldMap common open override fun <R> foldMap(M: Monoid<R>, source: S, map: (A) -> R): R
Map each target to a type R and use a Monoid to fold the results
get common abstract override fun get(source: S): A
Get the focus of a Getter
getAll common open fun getAll(source: S): List<A>
Get all targets of the Fold
getOrModify common open override fun getOrModify(source: S): Either<T, A>
Get the focus of a POptional or return the original value while allowing the type to change if it does not match
getOrNull common open fun getOrNull(source: S): A?
Get the focus of a POptional or null if the is not there
isEmpty common open fun isEmpty(source: S): Boolean
Check if there is no target
isNotEmpty common open fun isNotEmpty(source: S): Boolean
Check if there is at least one target
lastOrNull common open fun lastOrNull(source: S): A?
Get the last target or null
left common open override fun <C> left(): Getter<Either<S, C>, Either<A, C»
Create a sum of the Getter and type C
lift common open fun lift(map: (A) -> B): (S) -> T
Lift a function map: (A) -> B to the context of S: (S) -> T`
modify common open override fun modify(source: S, map: (A) -> B): T
Modify the focus of a POptional with a function map
modifyNullable common open fun modifyNullable(source: S, map: (A) -> B): T?
Modify the focus of a POptional with a function map
plus common open operator fun <C> plus(other: Fold<in A, out C>): Fold<S, C>
open operator fun <C> plus(other: Getter<in A, out C>): Getter<S, C>
open operator fun <C, D> plus(other: PEvery<in A, out B, out C, in D>): PEvery<S, T, C, D>
open operator fun <C, D> plus(other: PLens<in A, out B, out C, in D>): PLens<S, T, C, D>
open operator fun <C, D> plus(other: POptional<in A, out B, out C, in D>): POptional<S, T, C, D>
open operator fun <C, D> plus(other: PSetter<in A, out B, out C, in D>): PSetter<S, T, C, D>
open operator fun <C, D> plus(other: PTraversal<in A, out B, out C, in D>): PTraversal<S, T, C, D>
right common open override fun <C> right(): Getter<Either<C, S>, Either<C, A»
Create a sum of type C and the Getter
second common open override fun <C> second(): PLens<Pair<C, S>, Pair<C, T>, Pair<C, A>, Pair<C, B»
Create a product of a type C and the PLens
set common abstract override fun set(source: S, focus: B): T
Get the modified source of a POptional
setNullable common open fun setNullable(source: S, b: B): T?
Set the focus of a POptional with a value.
size common open fun size(source: S): Int
Calculate the number of targets
split common open infix fun <C, D> split(other: Getter<C, D>): Getter<Pair<S, C>, Pair<A, D»
Pair two disjoint Getter
common open infix fun <S1, T1, A1, B1> split(other: PLens<S1, T1, A1, B1>): PLens<Pair<S, S1>, Pair<T, T1>, Pair<A, A1>, Pair<B, B1»
Pair two disjoint PLens
zip common open infix fun <C> zip(other: Getter<S, C>): Getter<S, Pair<A, C»
Zip two Getter optics with the same source S

Properties

Name Summary
every common open val <U, V> PLens<U, V, S, T>.every: PTraversal<U, V, A, B>
DSL to compose Traversal with a Lens for a structure S to see all its foci A
every common open val <U, V> PIso<U, V, S, T>.every: PTraversal<U, V, A, B>
DSL to compose Traversal with a Iso for a structure S to see all its foci A
every common open val <U, V> PPrism<U, V, S, T>.every: PTraversal<U, V, A, B>
DSL to compose Traversal with a Prism for a structure S to see all its foci A
every common open val <U, V> POptional<U, V, S, T>.every: PTraversal<U, V, A, B>
DSL to compose Traversal with a Optional for a structure S to see all its foci A
every common open val <U, V> PSetter<U, V, S, T>.every: PSetter<U, V, A, B>
DSL to compose Traversal with a Setter for a structure S to see all its foci A
every common open val <U, V> PTraversal<U, V, S, T>.every: PTraversal<U, V, A, B>
DSL to compose Traversal with a Traversal for a structure S to see all its foci A
every common open val <U, V> PEvery<U, V, S, T>.every: PTraversal<U, V, A, B>
DSL to compose Traversal with a PEvery for a structure S to see all its foci A

Inheritors

Name
PIso

Extensions

Name Summary
get common operator fun <A, T> PLens<T, T, List<A>, List<A».get(i: Int): POptional<T, T, A, A>

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