Loop-recur in Kotlin

looprecur.kt

// Loop-recur enables recursive programming without the need of defining a recursive function

fun <A, R> loop(a: A, action: Loop1<A, R>.(A) -> R) = Loop1(action).recur(a)
class Loop1<A, R>(private val action: Loop1<A, R>.(A) -> R) {
    fun recur(a: A) = action(a)
}

fun main() {
    val n = readLine()!!.toInt()
    val fibn: Int = loop(n) { i ->
        when (i) {
            1, 2 -> 1
            else -> recur(i - 1) + recur(i - 2)
        }
    }
    println(fibn)
}