kotlin-stdlib / kotlin.collections / reduceRight

reduceRight

Common
JVM
JS
Native
1.0
inline fun <S, T : S> Array<out T>.reduceRight(
    operation: (T, acc: S) -> S
): S
inline fun ByteArray.reduceRight(
    operation: (Byte, acc: Byte) -> Byte
): Byte
inline fun ShortArray.reduceRight(
    operation: (Short, acc: Short) -> Short
): Short
inline fun IntArray.reduceRight(
    operation: (Int, acc: Int) -> Int
): Int
inline fun LongArray.reduceRight(
    operation: (Long, acc: Long) -> Long
): Long
inline fun FloatArray.reduceRight(
    operation: (Float, acc: Float) -> Float
): Float
inline fun DoubleArray.reduceRight(
    operation: (Double, acc: Double) -> Double
): Double
inline fun BooleanArray.reduceRight(
    operation: (Boolean, acc: Boolean) -> Boolean
): Boolean
inline fun CharArray.reduceRight(
    operation: (Char, acc: Char) -> Char
): Char
inline fun <S, T : S> List<T>.reduceRight(
    operation: (T, acc: S) -> S
): S
@ExperimentalUnsignedTypes inline fun UIntArray.reduceRight(
    operation: (UInt, acc: UInt) -> UInt
): UInt
@ExperimentalUnsignedTypes inline fun ULongArray.reduceRight(
    operation: (ULong, acc: ULong) -> ULong
): ULong
@ExperimentalUnsignedTypes inline fun UByteArray.reduceRight(
    operation: (UByte, acc: UByte) -> UByte
): UByte
@ExperimentalUnsignedTypes inline fun UShortArray.reduceRight(
    operation: (UShort, acc: UShort) -> UShort
): UShort

Accumulates value starting with last element and applying operation from right to left to each element and current accumulator value.

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val strings = listOf("a", "b", "c", "d")
println(strings.reduceRight { string, acc -> acc + string }) // dcba
println(strings.reduceRightIndexed { index, string, acc -> acc + string + index }) // dc2b1a0

// emptyList<Int>().reduceRight { _, _ -> 0 } //  will fail
//sampleEnd
}