multi-types.kt

fun main() {
    val words = listOf("a", "abc", "ab", "def", "abcd", "")
    val grouped = words
        .groupBy {
            when {
                it.isEmpty() -> WordType.Empty
                it.length <= 2 -> WordType.Shorter
                else -> WordType.Longer
            }
        }
        .mapValues { (_, words) -> words.size }

    // prints {Shorter=2, Longer=3, Empty=1}
    print(grouped)
}

enum class WordType {
    Longer, Shorter, Empty
}

shorter.kt

data class MyResponse(
    val longer: Int,
    val shorter: Int
)

fun main() {
    val words = listOf("a", "abc", "ab", "def", "abcd")
    val (longer, shorter) = words.partition { it.length > 2 }
    println(MyResponse(longer.size, shorter.size))
}