Product in Kotlin ported from Scala

Products.kt

interface Product {
  val productArity: Int
  fun elements(index: Int): Any?

  fun toList(): List<*> = productIterator().toList()

  fun productIterator(): Iterator<*> = object : Iterator<Any?> {
    var currIndex = 0
    override fun hasNext(): Boolean = currIndex < productArity
    override fun next(): Any? = elements(currIndex++)
  }

  fun productPrefix(): String = ""

}

interface Product1<out T1 : Any> : Product {
  override val productArity: Int
    get() = 1

  override fun elements(index: Int): Any = when (index) {
    0 -> first
    else -> throw IndexOutOfBoundsException(index.toString())
  }

  val first: T1
}

interface Product2<out A : Any, out B : Any> : Product {

  override val productArity: Int
    get() = 3

  override fun elements(index: Int): Any = when (index) {
    0 -> first
    1 -> second
    else -> throw IndexOutOfBoundsException(index.toString())
  }

  val first: A
  val second: B
}

interface Product3<out A : Any, out B : Any, out C : Any> : Product {

  override val productArity: Int
    get() = 3

  override fun elements(index: Int): Any = when (index) {
    0 -> first
    1 -> second
    2 -> third
    else -> throw IndexOutOfBoundsException(index.toString())
  }

  val first: A
  val second: B
  val third: C
}

interface Product4<out A : Any, out B : Any, out C : Any, out D : Any> : Product {

  override val productArity: Int
    get() = 3

  override fun elements(index: Int): Any = when (index) {
    0 -> first
    1 -> second
    2 -> third
    3 -> fourth
    else -> throw IndexOutOfBoundsException(index.toString())
  }

  val first: A
  val second: B
  val third: C
  val fourth: D
}