mapIndexedTo

Applies the given transform function to each element and its index in the original array and appends the results to the given destination.

@IgnorableReturnValueinline fun <T, R, C : MutableCollection<in R>> Array<out T>.mapIndexedTo(destination: C, transform: (index: Int, T) -> R): C(source)

val words = arrayOf("apple", "banana", "cherry")

val result = mutableListOf<String>().apply {
    words.mapIndexedTo(this) { index, word ->
        "$index: $word"
    }
}

println(result) // Output: [0: apple, 1: banana, 2: cherry]

Source