Result

Return type of a computation that could fail.

Result has two subclasses, Success and Failure. Success is used for successful computations. Failure is used for computations that have failed.

Result is dependent on two generic parameters; Error and Value. Error is a type that distinguishes between the kind of failures that could occur. Value is the type of successful computations.

Although Result is a sealed class and can be safely switched over, the idiomatic use is to build up a chain of results with the methods on this class. For an extended example check out this projects wiki.

Parameters

Error

the type that indicates which errors can occur.

Value

the type of a successful computation

Functions

andThen

fun <T> andThen(chain: (Value) -> Result<Error, T>): Result<Error, T>

Chain two computations togetherIf in a computation chain the result of one computation is needed as input for another computation, andThen is there to chain the computations together.

andThenError

fun <T> andThenError(chain: (Error) -> Result<T, Value>): Result<T, Value>

Chain two computations together for error recovery.

equals

open operator fun equals(other: Any?): Boolean

hashCode

open fun hashCode(): Int

map

fun <T> map(transform: (Value) -> T): Result<Error, T>

Transform a successful result.

mapError

fun <T> mapError(transform: (Error) -> T): Result<T, Value>

Transform a failed result.

orThrowException

fun orThrowException(exceptionProducer: (Error) -> Exception): Value

Unwrap the result by throwing an Exception that can depend on the kind of failureif a computation was a Success, return that data.

toString

open fun toString(): String

use

fun use(actOn: (Value) -> Unit): Result<Error, Value>

Use the data of a successful result.

useError

fun useError(actOn: (Error) -> Unit): Result<Error, Value>

Use the error of a failed result.

withDefault

fun withDefault(defaultValue: Value): Value

Unwrap the result by providing a default value.

fun withDefault(producer: (Error) -> Value): Value

Unwrap the result by providing a default value that can depend on the kind of failure.

Inheritors

Success

Failure

Result

See also

Parameters

Functions

Inheritors