Outcome

sealed interface Outcome<out T>

Represents the result of an operation that can either succeed with a value or fail with an error.

This sealed interface provides a robust way to handle operations that may produce a value or an error, offering a type-safe alternative to exceptions or nullable types. It includes utility functions for mapping, recovering, and folding outcomes, as well as converting to and from Result.

Parameters

The type of the value in a successful outcome.

Inheritors

Success

Failure

Types

Failure

data class Failure(val message: String, val throwable: Throwable? = null, val outcome: Outcome<*>? = null) : Outcome<Nothing>

Represents a failed outcome with an error message and optional cause.

Success

@JvmInline

value class Success<T>(val value: T) : Outcome<T>

Represents a successful outcome with a value.

Properties

failed

open val failed: Boolean

Indicates whether the operation failed (opposite of succeeded).

succeeded

abstract val succeeded: Boolean

Indicates whether the operation succeeded.

Functions

exceptionOrNull

open fun exceptionOrNull(): Throwable?

Returns the Throwable of a Failure or null if the outcome is a Success.

flatMap

inline suspend fun <T, R> Outcome<T>.flatMap(transform: suspend (T) -> Outcome<R>): Outcome<R>

Flat-maps the value of a successful Outcome using the provided transform function.

fold

inline suspend fun <T, R> Outcome<T>.fold(onSuccess: suspend (T) -> R, onFailure: suspend (String, Throwable?) -> R): R

Folds the Outcome into a single value by applying onSuccess for a Success or onFailure for a Failure.

getOrNull

open fun getOrNull(): T?

Returns the value of a Success or null if the outcome is a Failure.

map

inline suspend fun <T, R> Outcome<T>.map(transform: suspend (T) -> R): Outcome<R>

Maps the value of a successful Outcome using the provided transform function.

mapCatching

inline suspend fun <T, R> Outcome<T>.mapCatching(transform: suspend (T) -> R): Outcome<R>

Maps the value of a successful Outcome using the provided transform function, catching any exceptions.

mapFailure

inline suspend fun <T> Outcome<T>.mapFailure(transform: suspend (Outcome.Failure) -> Outcome.Failure): Outcome<T>

Maps a Failure using the provided transform function, leaving Success unchanged.

recover

inline suspend fun <T> Outcome<T>.recover(recoverBlock: suspend (Outcome.Failure) -> T): Outcome<T>

Recovers from a Failure by applying the recoverBlock function to produce a new value.

recoverCatching

inline suspend fun <T> Outcome<T>.recoverCatching(recoverBlock: suspend (Outcome.Failure) -> T): Outcome<T>

Recovers from a Failure by applying the recoverBlock function, catching any exceptions.

toResult

open fun toResult(): Result<T>

Converts this Outcome to a Result.