Outcome

sealed class Outcome<out E, out A>(source)

Outcome is a type that represents three possible states a result can be in: Present, Absent or Failure. Under the hood it wraps the type Either<E, Option<A>> and supports the common functions that Eithers and Options support such as map, flatMap and zip.

There are three primary constructors:

data class Present<A>(val value: A) : Outcome<Nothing, A>
data class Failure<E>(val error: E) : Outcome<E, Nothing>
object Absent : Outcome<Nothing, Nothing>

or you can use the extension methods thusly:

A.present()
E.failure()

You can also easily convert an Either<Option<A>> to an Outcome using toOutcome()

val outcome = "hi".some().right().toOutcome()

There is also a type alias OutcomeOf<A> which specialises the error side to a Throwable for your convenience.

Inheritors

Present

Failure

Absent

Types

Companion

object Companion

Properties

inner

val inner: Either<E, Option<A>>

Functions

asEither

inline fun <E, A> Outcome<E, A>.asEither(onAbsent: () -> E): Either<E, A>

asOption

fun <E, A> Outcome<E, A>.asOption(): Option<A>

Converts an Outcome to an option treating Failure as Absent

filter

inline fun <A, E> Outcome<E, A>.filter(p: (A) -> Boolean): Outcome<E, A>

flatMap

inline fun <A, E, B> Outcome<E, A>.flatMap(f: (A) -> Outcome<E, B>): Outcome<E, B>

FlatMap allows multiple Outcomes to be safely chained together, passing the value from the previous as input into the next function that produces an Outcome

flatTap

inline fun <A, E, B> Outcome<E, A>.flatTap(f: (A) -> Outcome<E, B>): Outcome<E, A>

Performs a flatMap across the supplied function, propagating failures or absence but preserving the original present value.

flatten

fun <A, E> Outcome<E, Outcome<E, A>>.flatten(): Outcome<E, A>

fold

inline fun <E, A, B> Outcome<E, A>.fold(onFailure: (E) -> B, onAbsent: () -> B, onPresent: (A) -> B): B

foldOption

inline fun <E, A, B> Outcome<E, A>.foldOption(onAbsent: () -> B, onPresent: (A) -> B): Either<E, B>

getOrElse

inline fun <E, A> Outcome<E, A>.getOrElse(onAbsentOrFailure: () -> A): A

isAbsent

fun isAbsent(): Boolean

isFailure

fun isFailure(): Boolean

isPresent

fun isPresent(): Boolean

map

inline fun <B> map(f: (A) -> B): Outcome<E, B>

Map safely transforms a value in the Outcome. It has no effect on Absent or Failure instances.

mapFailure

inline fun <E, A, EE> Outcome<E, A>.mapFailure(f: (E) -> EE): Outcome<EE, A>

onAbsentHandle

inline fun <E, A> Outcome<E, A>.onAbsentHandle(onAbsent: () -> Outcome<E, A>): Outcome<E, A>

onFailureHandle

inline fun <E, A> Outcome<E, A>.onFailureHandle(onFailure: (E) -> Outcome<E, A>): Outcome<E, A>

optionOrThrow

fun <A> Outcome<Throwable, A>.optionOrThrow(): Option<A>

orThrow

inline fun <A> Outcome<Throwable, A>.orThrow(onAbsent: () -> Throwable): A

recover

inline fun <E, A, EE> Outcome<E, A>.recover(block: OutcomeRaise<EE>.(E) -> A): Outcome<EE, A>

sequence

fun <E, EE, A> Outcome<E, Either<EE, A>>.sequence(): Either<EE, Outcome<E, A>>

fun <E, A> Outcome<E, Option<A>>.sequence(): Option<Outcome<E, A>>

fun <E, EE, A> Outcome<E, Validated<EE, A>>.sequence(): Validated<EE, Outcome<E, A>>

fun <E, A> Outcome<E, Iterable<A>>.sequence(): List<Outcome<E, A>>

tap

inline fun <B> tap(f: (A) -> B): Outcome<E, A>

Performs an effect over the value and preserves the original Outcome

tapAbsent

inline fun <A, B, E> Outcome<E, A>.tapAbsent(f: () -> B): Outcome<E, A>

tapFailure

inline fun <A, B, E> Outcome<E, A>.tapFailure(f: (E) -> B): Outcome<E, A>

traverse

inline fun <E, EE, A, B> Outcome<E, A>.traverse(f: (A) -> Either<EE, B>): Either<EE, Outcome<E, B>>

inline fun <E, A, B> Outcome<E, A>.traverse(f: (A) -> Option<B>): Option<Outcome<E, B>>

inline fun <E, EE, A, B> Outcome<E, A>.traverse(f: (A) -> Validated<EE, B>): Validated<EE, Outcome<E, B>>

inline fun <E, A, B> Outcome<E, A>.traverse(f: (A) -> List<B>): List<Outcome<E, B>>

zip

inline fun <E, A, B, C> Outcome<E, A>.zip(other: Outcome<E, B>, f: (A, B) -> C): Outcome<E, C>

Zip allows you to combine two or more Outcomes easily with a supplied function.

inline fun <E, A, B, C, D> Outcome<E, A>.zip(o1: Outcome<E, B>, o2: Outcome<E, C>, crossinline f: (A, B, C) -> D): Outcome<E, D>

inline fun <E, A, B, C, D, EE> Outcome<E, A>.zip(o1: Outcome<E, B>, o2: Outcome<E, C>, o3: Outcome<E, D>, crossinline f: (A, B, C, D) -> EE): Outcome<E, EE>

inline fun <E, A, B, C, D, EE, F> Outcome<E, A>.zip(o1: Outcome<E, B>, o2: Outcome<E, C>, o3: Outcome<E, D>, o4: Outcome<E, EE>, crossinline f: (A, B, C, D, EE) -> F): Outcome<E, F>