Answer by Mariell Hoversholm for Kotlin: convert from int to Enum

The easiest way would be using first (it also has a firstOrNull alternative) like so:

val results = ints.mapIndexed { idx, e -> getRomanDigit(e, Rank.values().first { it.value == ints.size - idx }) }// Or using a map for caching:val ranks = Rank.values().map { it.value to it }.toMap()val results = ints.mapIndexed { idx, e -> getRomanDigit(e, ranks[ints.size - idx]!!) }

This however seems like a case where you'd rather want a data class for the rank, as you cannot possibly map all possible values of ints.size - idx in enumerations:

data class Rank(val value: Int)val results = ints.mapIndexed { idx, e -> getRomanDigit(e, Rank(ints.size - idx) }