App.kt

fun main(args: Array<String>) {
    println("Foldwhile experiment")

    val oneTo100 = 1 until 100

    println(oneTo100.fold(0) { acc, v -> acc + v})

    println("Stop folding when total is above 2000")

    println(oneTo100.foldWhile(0, { acc, v -> acc + v }, { acc, _ -> acc < 2000 }))

}

private fun <T, V> Iterable<T>.foldWhile(initial: V, operation: (V, T) -> V, predicate: (V,T) -> Boolean) : V {
    return this.fold(initial) { acc, v ->
        if(predicate(acc, v)) {
            operation(acc, v)
        } else {
            return acc
        }
    }
}