Kotlin utilities/it.czerwinski.kotlin.util/None

None

object None : Option<Nothing>

Representation of a non-existent value.

Functions

all

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

Returns the result of applying the predicate to the value if this is Some or true if this is None.

any

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

Returns the result of applying the predicate to the value if this is Some or false if this is None.

asIterable

open override fun asIterable(): Iterable<Nothing>

Returns an iterable that wraps this Option returning its value if it is defined, or an empty iterable if the option is empty.

asSequence

open override fun asSequence(): Sequence<Nothing>

Returns a sequence that wraps this Option returning its value if it is defined, or an empty sequence if the option is empty.

filter

inline fun filter(predicate: (Nothing) -> Boolean): Option<Nothing>

Returns the same Some if the predicate is satisfied for the value. Otherwise returns a None.

filterIsInstance

inline fun <R> filterIsInstance(): Option<R>

Returns the same Some casted to type R if it is R. Otherwise returns a None.

filterNot

inline fun filterNot(predicate: (Nothing) -> Boolean): Option<Nothing>

Returns the same Some if the predicate is not satisfied for the value. Otherwise returns a None.

flatMap

inline fun <R> flatMap(transform: (Nothing) -> Option<R>): Option<R>

Maps value of a Some to a new Option using transform or returns the same None.

fold

inline fun <R> fold(default: R, transform: (Nothing) -> R): R

Returns result of applying transform on the value of Some or default if this is None.

inline fun <R> fold(default: () -> R, transform: (Nothing) -> R): R

Returns result of applying transform on the value of Some or default if this is None.

forEach

inline fun forEach(action: (Nothing) -> Unit)

Runs action if this is a Some. Returns Unit without any action if this is None.

get

open override fun get(): Nothing

Gets the value of a Some or throws an exception.

getOrNull

open override fun getOrNull(): Nothing?

Gets the value of a Some or null if this is a None.

iterator

open override fun iterator(): Iterator<Nothing>

Returns a singleton iterator returning the option's value if it is defined, or an empty iterator if the option is empty.

map

inline fun <R> map(transform: (Nothing) -> R): Option<R>

Maps value of a Some using transform or returns the same None.

none

inline fun none(predicate: (Nothing) -> Boolean): Boolean

Returns false if the predicate is met by the value if this is Some or true otherwise.

toLeft

inline fun <R> toLeft(right: () -> R): Either<Nothing, R>

Returns a Right containing the given argument right if this is empty, or a Left containing this option's value if it is defined.

toList

open override fun toList(): List<Nothing>

Returns a singleton list containing the option's value if it is defined, or an empty list if the option is empty.

toRight

inline fun <L> toRight(left: () -> L): Either<L, Nothing>

Returns a Left containing the given argument left if this is empty, or a Right containing this option's value if it is defined.

toString

open override fun toString(): String

zip

infix fun <R> zip(other: Option<R>): Option<Pair<Nothing, R>>

Returns Some containing a Pair of values of this and other if both Options are Some. Otherwise returns None.

inline fun <T1, R> zip(other: Option<T1>, transform: (Nothing, T1) -> R): Option<R>

Returns Some containing the result of applying transform to both values of this and other if both Options are Some. Otherwise returns None.

Properties

isDefined

val isDefined: Boolean

Returns true if the option is Some. Otherwise returns false.

isEmpty

open override val isEmpty: Boolean = true

Returns true if the option is None. Otherwise returns false.

isNotEmpty

val isNotEmpty: Boolean

Returns true if the option is Some. Otherwise returns false.