inFullMobile Language Wars: Round 1 - Kotlin Solution 1 by @rainqer - See: https://gist.github.com/rsp/d8bdbafa09f24f99eebc8ed60fe205c8

ifm-lw-r1-kotlin-solution-1.kt

package com.infullmobile.languagewars

fun f(a: ((Int) -> Int) -> ((Int) -> Int)): ((Int) -> Int) -> (Int) -> Int {
    val invocationCount = a(increment)(0)
    return if (invocationCount > 0) { x: (Int) -> Int -> { input -> applyXTimes(x, invocationCount - 1)(input) } }
    else { _ -> { input -> input } }
}

fun applyXTimes(x: (Int) -> Int, count: Int): (Int) -> Int
        = { argument -> (1..count).fold(argument, { acc, _ -> x(acc) }) }

val increment: (Int) -> Int = { counter -> counter + 1 }