//arrow-optics/arrow.optics/PPrism

PPrism

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

A Prism is a loss less invertible optic that can look into a structure and optionally find its focus. Mostly used for finding a focus that is only present under certain conditions i.e. list head Prism, Int>

A (polymorphic) PPrism is useful when setting or modifying a value for a polymorphic sum type i.e. PPrism, Option, String, Int>

A PPrism gathers the two concepts of pattern matching and constructor and thus can be seen as a pair of functions:

  • getOrModify: A -> Either<A, B> meaning it returns the focus of a PPrism OR the original value
  • reverseGet : B -> A meaning we can construct the source type of a PPrism from a focus B

Parameters

common

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

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 <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, 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: 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: PPrism<in A, out B, out C, in D>): PPrism<S, T, C, D>
Compose a PPrism with another PPrism
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(): PPrism<Pair<S, C>, Pair<T, C>, Pair<A, C>, Pair<B, C»
Create a product of the PPrism 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
getAll common open fun getAll(source: S): List<A>
Get all targets of the Fold
getOrModify common abstract 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(): PPrism<Either<S, C>, Either<T, C>, Either<A, C>, Either<B, C»
Create a sum of the PPrism and a 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`
liftNullable common open fun liftNullable(f: (A) -> B): (S) -> T?
Lift a function f: (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 PPrism with a function
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, D> plus(other: PEvery<in A, out B, out C, in D>): PEvery<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: PPrism<in A, out B, out C, in D>): PPrism<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>
reverseGet common abstract fun reverseGet(focus: B): T
right common open override fun <C> right(): PPrism<Either<C, S>, Either<C, T>, Either<C, A>, Either<C, B»
Create a sum of a type C and the PPrism
second common open override fun <C> second(): PPrism<Pair<C, S>, Pair<C, T>, Pair<C, A>, Pair<C, B»
Create a product of a type C and the PPrism
set common open override fun set(source: S, focus: B): T
Set the focus of a PPrism with a value
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

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

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