Maybe

sealed interface Maybe<out Element>(source)

Container interface that is used to describe that there is either some value wrapped in the data class Some or the None data object. It's a copy of Option from Rust stdlib.

Why not just use E? instead of Maybe<E>? The reason is simple. If you E is nullable and you have possibility of having either element of type E or a null, then you won't distinguish null as possible value and null as absence of such value. That's why you should write Maybe<E> and then you'll be able to distinguish null from None.

Inheritors

Some

None

Functions

flatten

fun <Element> Maybe<Maybe<Element>>.flatten(): Maybe<Element>

Returns the wrapped in Some instance of type Maybe<E> if it is present or None otherwise.

ifSome

inline fun <Element> Maybe<Element>.ifSome(block: (Element) -> Unit)

Runs the block on the value if it is present.

isNone

fun Maybe<*>.isNone(): Boolean

Returns true if the value is absent.

isSome

fun Maybe<*>.isSome(): Boolean

Returns true if the value is present.

map

inline fun <Element, Result> Maybe<Element>.map(compute: (Element) -> Result): Maybe<Result>

Computes the compute on the value and returns it wrapped in Some if the value is present or just returns None otherwise.

mapOrDefault

inline fun <Element, Result> Maybe<Element>.mapOrDefault(default: Result, compute: (Element) -> Result): Result

Computes the compute on the value and returns it if the value is present or just returns default result otherwise.

mapOrElse

inline fun <Element, Result> Maybe<Element>.mapOrElse(default: () -> Result, compute: (Element) -> Result): Result

Computes the compute on the value and returns result of the computation if the value is present or just computes and returns default result otherwise.

orDefault

fun <Element> Maybe<Element>.orDefault(default: Element): Element

Returns the value if it is present or default one otherwise.

orElse

inline fun <Element> Maybe<Element>.orElse(default: () -> Element): Element

Returns the value if it is present or computes and returns default one otherwise.

orThrow

inline fun <Element> Maybe<Element>.orThrow(error: () -> Throwable): Element

Returns the value if it is present or throws the provided exception otherwise.