Package it.czerwinski.kotlin.util

Contains utility types based on Scala.

Types

Either

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sealed class Either<out L, out R>

Disjoint union.

Failure

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data class Failure(exception: Throwable) : Try<Nothing>

Left

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data class Left<out L>(value: L) : Either<L, Nothing>

LeftProjection

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data class LeftProjection<out L, out R>(either: Either<L, R>)

None

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object None : Option<Nothing>

Representation of a non-existent value.

Option

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sealed class Option<out T>

Representation of an optional value.

Right

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data class Right<out R>(value: R) : Either<Nothing, R>

RightProjection

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data class RightProjection<out L, out R>(either: Either<L, R>)

Some

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data class Some<T>(value: T) : Option<T>

Representation of a value of type T.

Success

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data class Success<out T>(value: T) : Try<T>

Try

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sealed class Try<out T>

Representation of an operation that might successfully return a value or throw an exception.

Functions

asOption

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fun <T> T?.asOption(): Option<T>

Returns Some if this is not null or None if this is null.

contains

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operator fun <T> Option<T>.contains(element: T): Boolean

Tests whether the Option contains the given element.

evert

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fun <T> Option<Try<T>>.evert(): Try<Option<T>>

Moves inner Try outside of the outer Option.

fun <T> Try<Option<T>>.evert(): Option<Try<T>>

Moves inner Option outside of the outer Try.

filterNotNull

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fun <L, R> Either<L, R?>.filterNotNull(): Either<L, R>?

Returns the same Right if its value is not null.

fun <L, R> LeftProjection<L?, R>.filterNotNull(): Either<L, R>?

Returns the same Left if its value is not null.

fun <L, R> RightProjection<L, R?>.filterNotNull(): Either<L, R>?

Returns the same Right if its value is not null.

fun <T> Try<T?>.filterNotNull(): Try<T>

Returns the same Success if its value is not null.

filterNotNullToOption

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fun <L, R> Either<L, R?>.filterNotNullToOption(): Option<Either<L, R>>

Returns Some containing the same Right if its value is not null.

fun <L, R> LeftProjection<L?, R>.filterNotNullToOption(): Option<Either<L, R>>

Returns Some containing the same Left if its value is not null.

fun <L, R> RightProjection<L, R?>.filterNotNullToOption(): Option<Either<L, R>>

Returns Some containing the same Right if its value is not null.

filterOrElse

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inline fun <L, R> Either<L, R>.filterOrElse(predicate: (R) -> Boolean, zero: () -> L): Either<L, R>?

Returns the same Right if the predicate is satisfied for the value, Left(zero) if the predicate is not satisfied for the value, or the same Left if this is Left.

inline fun <L, R> LeftProjection<L, R>.filterOrElse(predicate: (L) -> Boolean, zero: () -> R): Either<L, R>?

Returns the same Left if the predicate is satisfied for the value, Right(zero) if the predicate is not satisfied for the value, or the same Right if this is Right.

inline fun <L, R> RightProjection<L, R>.filterOrElse(predicate: (R) -> Boolean, zero: () -> L): Either<L, R>?

Returns the same Right if the predicate is satisfied for the value, Left(zero) if the predicate is not satisfied for the value, or the same Left if this is Left.

flatMap

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inline fun <L, R, T> Either<L, R>.flatMap(transform: (R) -> Either<L, T>): Either<L, T>

Maps value of this Right to a new Either using transform.

inline fun <L, R, T> LeftProjection<L, R>.flatMap(transform: (L) -> Either<T, R>): Either<T, R>

Maps value of this Left to a new Either using transform.

inline fun <L, R, T> RightProjection<L, R>.flatMap(transform: (R) -> Either<L, T>): Either<L, T>

Maps value of this Right to a new Either using transform.

flatten

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fun <T> Option<Option<T>>.flatten(): Option<T>

Transforms a nested Option to a not nested Option.

fun <T> Option<Try<T>>.flatten(): Option<T>

Returns Some if this Some contains a Success.

fun <T> Option<Iterable<T>>.flatten(): List<T>

Returns nested List if this is Some.

fun <T> Try<Option<T>>.flatten(): Option<T>

Extracts an Option nested in the Try to a not nested Option.

fun <T> Try<Try<T>>.flatten(): Try<T>

Transforms a nested Try to a not nested Try.

fun <T> Iterable<Option<T>>.flatten(): List<T>

Returns List of values of each Some in this Iterable.

getOrElse

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inline fun <L, R> Either<L, R>.getOrElse(default: () -> R): R

Gets value of this Right or default value if this is Left.

inline fun <L, R> LeftProjection<L, R>.getOrElse(default: () -> L): L

Gets value of this Left or default value if this is Right.

inline fun <T> Option<T>.getOrElse(default: () -> T): T

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

inline fun <L, R> RightProjection<L, R>.getOrElse(default: () -> R): R

Gets value of this Right or default value if this is Left.

inline fun <T> Try<T>.getOrElse(default: () -> T): T

Gets the value of a Success or default value if this is a Failure.

joinLeft

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fun <L, R> Either<Either<L, R>, R>.joinLeft(): Either<L, R>

Returns this if this is Right.

joinRight

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fun <L, R> Either<L, Either<L, R>>.joinRight(): Either<L, R>

Returns this if this is Left.

merge

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fun <T> Either<T, T>.merge(): T

Merges Left and Right of the same type to a single value.

orElse

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inline fun <T> Option<T>.orElse(default: () -> Option<T>): Option<T>

Returns this Option if this is a Some or default if this is None.

inline fun <T> Try<T>.orElse(default: () -> Try<T>): Try<T>

Returns this Try if this is a Success or default if this is a Failure.

recover

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inline fun <T> Try<T>.recover(rescue: (Throwable) -> T): Try<T>

Returns this Try if this is a Success or a Try created for the rescue operation if this is a Failure.

recoverWith

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inline fun <T> Try<T>.recoverWith(rescue: (Throwable) -> Try<T>): Try<T>

Returns this Try if this is a Success or a Try created by the rescue function if this is a Failure.

unzip

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fun <A, B> Option<Pair<A, B>>.unzip(): Pair<Option<A>, Option<B>>

Transforms an Option of a Pair into a Pair of an Option of the first value and an Option of the second value.

fun <A, B, C> Option<Triple<A, B, C>>.unzip(): Triple<Option<A>, Option<B>, Option<C>>

Transforms an Option of a Triple into a Triple of an Option of the first value, an Option of the second value, and an Option of the third value.