Mastering High Performance with Kotlin

Utility functions

The _Ranges.kt file contains many utility functions for the IntProgression, LongProgression, and CharProgression classes. For instance, the reversed() function:

public fun IntProgression.reversed(): IntProgression {    return IntProgression.fromClosedRange(last, first, -step)}public fun LongProgression.reversed(): LongProgression {    return LongProgression.fromClosedRange(last, first, -step)}public fun CharProgression.reversed(): CharProgression {    return CharProgression.fromClosedRange(last, first, -step)}

One use of this function might look as follows:

fun main(args: Array<String>) {    val value = args[0].toInt()        if (value in (0..10).reversed()) {        println(value)    }}

Decompiled to Java, it looks like this:

public final class