run.smt.ktest.util.functional.Either.Either.kt Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of ktest-util Show documentation

kTest utilities

There is a newer version: 1.0.0

package run.smt.ktest.util.functional.Either

import run.smt.ktest.util.functional.identity

fun  left(left: A): Either = Left(left)
fun  right(right: B): Either = Right(right)

sealed class Either {
    abstract val left: A?
    abstract val right: B?
    abstract val isRight: Boolean
    abstract val flip: Either
    val isLeft: Boolean = !isRight

    inline fun  bimap(leftMapper: (A) -> AA, rightMapper: (B) -> BB): Either
        = if (isLeft) left(leftMapper(left!!)) else right(rightMapper(right!!))

    inline fun  mapLeft(mapper: (A) -> AA): Either = bimap(mapper, identity())
    inline fun  mapRight(mapper: (B) -> BB): Either = bimap(identity(), mapper)

    inline fun  unify(leftMapper: (A) -> C, rightMapper: (B) -> C): C
        = if (isRight) rightMapper(right!!) else leftMapper(left!!)
}

private class Left(override val left: A) : Either() {
    override val right: B? = null
    override val isRight: Boolean = false
    override val flip: Either by lazy { Right(left) }
}

private class Right(override val right: B) : Either() {
    override val left: A? = null
    override val isRight: Boolean = true
    override val flip: Either by lazy { Left(right) }
}