Sum digits of a given number in Kotlin

SumOfDigits.kt

/*

In mathematics, the digit sum of a given integer is the sum of all its digits (e.g.
the digit sum of 84001 is calculated as 8+4+0+0+1 = 13).

Write a function that will get an integer and will return the digit sum for that integer.
 */
fun main(args: Array<String>) {
    sumOfDigits("84001");
}

fun sumOfDigits(n: String) {
    val arr = n.toList()
    val arrOfInt = arr.map{ it.toString().toInt() }
    print(arrOfInt.sum())
}

You could also use the sumBy() function like: val sum: Int = input.sumBy { it - '0' }