kotlin-stdlib / kotlin.text / reduceRightOrNull

reduceRightOrNull

Common
JVM
JS
Native
1.3
@ExperimentalStdlibApi inline fun CharSequence.reduceRightOrNull(
    operation: (Char, acc: Char) -> Char
): Char?

Accumulates value starting with last character and applying operation from right to left to each character and current accumulator value. Returns null if the char sequence is empty.

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val strings = listOf("a", "b", "c", "d")
println(strings.reduceRightOrNull { string, acc -> acc + string }) // dcba

println(emptyList<String>().reduceRightOrNull { _, _ -> "" }) // null
//sampleEnd
}