replaceAll

Replaces each element in the list with a result of a transformation specified.

@ExperimentalNativeApiactual fun <T> MutableList<T>.replaceAll(transformation: (T) -> T)(source)
import kotlin.experimental.ExperimentalNativeApi

fun main() {
    val numbers = mutableListOf(1, 2, 3, 4)
    numbers.replaceAll { it * 2 }
    println(numbers)   // Output: [2, 4, 6, 8]
}

Source