Variant of Either.catchOrThrow constructor that allows for working with Either<Throwable, A> by transforming or recovering from Throwable as T in the Either.Left side. This API is the same as recover. This is useful when working with results of Either.catch since this API offers a reified variant.

combine

inline fun <A, B> Either<A, B>.combine(other: Either<A, B>, combineLeft: (A, A) -> A, combineRight: (B, B) -> B): Either<A, B>

Combine two Either values. If both are Right then combine both B values using combineRight or if both are Left then combine both A values using combineLeft, otherwise return the sole Left value (either this or other).

compareTo

operator fun <A : Comparable<A>, B : Comparable<B>> Either<A, B>.compareTo(other: Either<A, B>): Int

flatMap

inline fun <A, B, C> Either<A, B>.flatMap(f: (right: B) -> Either<A, C>): Either<A, C>

Binds the given function across Right, that is, 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.

flatten

fun <A, B> Either<A, Either<A, B>>.flatten(): Either<A, B>

fold

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.

getOrElse

infix 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.

getOrNone

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.

getOrNull

fun getOrNull(): Nothing?

Returns the unwrapped value B of Either.Right or null if it is Either.Left.

handleErrorWith

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

Binds the given function across Left, that is, Map, or transform, the left value A of this Either into a new Either with a left value of type C. Returns a new Either with either the original right value of type B or the newly transformed left value of type C.

isLeft

fun isLeft(): Boolean

Returns true if this is a Left, false otherwise.

inline fun isLeft(predicate: (A) -> Boolean): Boolean

Returns false if Right or returns the result of the given predicate to the Left value.

isRight

fun isRight(): Boolean

Returns true if this is a Right, false otherwise.

inline fun isRight(predicate: (Nothing) -> Boolean): Boolean

Returns false if Left or returns the result of the given predicate to the Right value.

leftOrNull

fun leftOrNull(): A?

Returns the unwrapped value A of Either.Left or null if it is Either.Right.

map

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.

mapLeft

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.

merge

fun <A> Either<A, A>.merge(): A

Returns the value from this Right or Left.

onLeft

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.

onRight

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.

recover

inline fun <E, EE, A> Either<E, A>.recover(recover: Raise<EE>.(E) -> A): Either<EE, A>

Recover from any Either.Left if encountered.

swap

fun swap(): Either<Nothing, A>

Swap the generic parameters A and B of this Either.

toEitherNel

fun <E, A> Either<E, A>.toEitherNel(): EitherNel<E, A>

toIor

fun toIor(): Ior<A, Nothing>

toString

open override fun toString(): String

validate

fun validate(validation: Raise<A>.(Nothing) -> Unit): Either<A, Nothing>

Runs some validation, expressed as a lambda that may raise, on Right values. If the validation is successful, the value is left unchanged. The main use case is in combination with ensure and other validation functions.