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package ca.allanwang.kau.utils
/**
* Created by Allan Wang on 2017-06-17.
*
* Courtesy of adelnizamutdinov
*
* https://github.com/adelnizamutdinov/kotlin-either
*/
@Suppress("unused")
sealed class Either<out L, out R>
data class Left<out T>(val value: T) : Either<T, Nothing>()
data class Right<out T>(val value: T) : Either<Nothing, T>()
inline fun <L, R, T> Either<L, R>.fold(left: (L) -> T, right: (R) -> T): T =
when (this) {
is Left -> left(value)
is Right -> right(value)
}
inline fun <L, R, T> Either<L, R>.flatMap(f: (R) -> Either<L, T>): Either<L, T> =
fold({ this as Left }, f)
inline fun <L, R, T> Either<L, R>.map(f: (R) -> T): Either<L, T> =
flatMap { Right(f(it)) }
val <T> Either<T, *>.isLeft: Boolean
get() = this is Left<T>
val <T> Either<*, T>.isRight: Boolean
get() = this is Right<T>
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