arrow-core/arrow.core/Either/Left

Left

data class Left<out A>(val value: A) : Either<A, Nothing> (source)

The left side of the disjoint union, as opposed to the Right side.

Constructors

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fun <out A> Left(value: A)

Types

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object Companion

Functions

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inline fun <C> fold(ifLeft: (left: A) -> C, ifRight: (right: Nothing) -> C): C

Transform an Either into a value of C. Alternative to using when to fold an Either into a value C.

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fun getOrNone(): Option<Nothing>

Transforms Either into Option, where the encapsulated value B is wrapped in Some when this instance represents Either.Right, or None if it is Either.Left.

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fun getOrNull(): Nothing?

Returns the encapsulated value B if this instance represents Either.Right or null if it is Either.Left.

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fun isLeft(): Boolean
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fun isRight(): Boolean
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inline fun <C> map(f: (right: Nothing) -> C): Either<A, C>

Map, or transform, the right value B of this Either to a new value C.

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inline fun <C> mapLeft(f: (A) -> C): Either<C, Nothing>

Map, or transform, the left value A of this Either to a new value C.

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inline fun onLeft(action: (left: A) -> Unit): Either<A, Nothing>

Performs the given action on the encapsulated A if this instance represents Either.Left. Returns the original Either unchanged.

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inline fun onRight(action: (right: Nothing) -> Unit): Either<A, Nothing>

Performs the given action on the encapsulated B value if this instance represents Either.Right. Returns the original Either unchanged.

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fun swap(): Either<Nothing, A>

Swap the generic parameters A and B of this Either.

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open override fun toString(): String
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inline fun <AA, C> traverse(fa: (Nothing) -> Validated<AA, C>): Validated<AA, Either<A, C>>

Properties

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val value: A

Extensions

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fun <A, B> Either<A?, B?>.bisequenceNullable(): Either<A, B>?
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fun <A, B> Either<A, B>.combine(SGA: Semigroup<A>, SGB: Semigroup<B>, b: Either<A, B>): Either<A, B>
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fun <A, B> Either<A, B>.combineK(y: Either<A, B>): Either<A, B>
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operator fun <A : Comparable<A>, B : Comparable<B>> Either<A, B>.compareTo(other: Either<A, B>): Int
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inline fun <A, B, C> Either<A, B>.flatMap(f: (right: B) -> Either<A, C>): Either<A, C>

Map, or transform, the right value B of this Either into a new Either with a right value of type C. Returns a new Either with either the original left value of type A or the newly transformed right value of type C.

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fun <A, B> Either<A, Either<A, B>>.flatten(): Either<A, B>
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inline fun <A, B> Either<A, B>.getOrElse(default: (A) -> B): B

Get the right value B of this Either, or compute a default value with the left value A.

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inline fun <A, B> Either<A, B>.handleError(f: (A) -> B): Either<A, B>
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inline fun <A, B, C> Either<A, B>.handleErrorWith(f: (A) -> Either<C, B>): Either<C, B>
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fun <AA, A : AA, B> Either<A, B>.leftWiden(): Either<AA, B>
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inline fun <A> Either<A, A>.merge(): A

Returns the value from this Right or Left.

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inline fun <A, B, C> Either<A, B>.redeem(fe: (A) -> C, fa: (B) -> C): Either<A, C>
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inline fun <A, B, C, D> Either<A, B>.redeemWith(fa: (A) -> Either<C, D>, fb: (B) -> Either<C, D>): Either<C, D>
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fun <A, B, C> Either<A, Validated<B, C>>.sequence(): Validated<B, Either<A, C>>
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fun <A, C, B : C> Either<A, B>.widen(): Either<A, C>

Given B is a sub type of C, re-type this value from Either to Either

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fun <A, B, C, D> Either<A, B>.zip(fb: Either<A, C>, f: (B, C) -> D): Either<A, D>
fun <A, B, C> Either<A, B>.zip(fb: Either<A, C>): Either<A, Pair<B, C>>
inline fun <A, B, C, D, E> Either<A, B>.zip(c: Either<A, C>, d: Either<A, D>, map: (B, C, D) -> E): Either<A, E>
inline fun <A, B, C, D, E, F> Either<A, B>.zip(c: Either<A, C>, d: Either<A, D>, e: Either<A, E>, map: (B, C, D, E) -> F): Either<A, F>
inline fun <A, B, C, D, E, F, G> Either<A, B>.zip(c: Either<A, C>, d: Either<A, D>, e: Either<A, E>, f: Either<A, F>, map: (B, C, D, E, F) -> G): Either<A, G>
inline fun <A, B, C, D, E, F, G, H> Either<A, B>.zip(c: Either<A, C>, d: Either<A, D>, e: Either<A, E>, f: Either<A, F>, g: Either<A, G>, map: (B, C, D, E, F, G) -> H): Either<A, H>
inline fun <A, B, C, D, E, F, G, H, I> Either<A, B>.zip(c: Either<A, C>, d: Either<A, D>, e: Either<A, E>, f: Either<A, F>, g: Either<A, G>, h: Either<A, H>, map: (B, C, D, E, F, G, H) -> I): Either<A, I>
inline fun <A, B, C, D, E, F, G, H, I, J> Either<A, B>.zip(c: Either<A, C>, d: Either<A, D>, e: Either<A, E>, f: Either<A, F>, g: Either<A, G>, h: Either<A, H>, i: Either<A, I>, map: (B, C, D, E, F, G, H, I) -> J): Either<A, J>
inline fun <A, B, C, D, E, F, G, H, I, J, K> Either<A, B>.zip(c: Either<A, C>, d: Either<A, D>, e: Either<A, E>, f: Either<A, F>, g: Either<A, G>, h: Either<A, H>, i: Either<A, I>, j: Either<A, J>, map: (B, C, D, E, F, G, H, I, J) -> K): Either<A, K>
inline fun <A, B, C, D, E, F, G, H, I, J, K, L> Either<A, B>.zip(c: Either<A, C>, d: Either<A, D>, e: Either<A, E>, f: Either<A, F>, g: Either<A, G>, h: Either<A, H>, i: Either<A, I>, j: Either<A, J>, k: Either<A, K>, map: (B, C, D, E, F, G, H, I, J, K) -> L): Either<A, L>