interface Monoid<T : Any?> : Semigroup<T> {
  abstract val unit: T
    abstract get

}

interface Semigroup<T : Any?> {
  abstract infix fun T.combine(other: T): T

}

object IntMonoid : Monoid<Int> {
  override val unit: Int
    field = 0
    override get

  private constructor() /* primary */ {
    super/*Any*/()
    /* <init>() */

  }

  override infix fun Int.combine(other: Int): Int {
    return <this>.plus(other = other)
  }

}

object StringMonoid : Monoid<String> {
  override val unit: String
    field = ""
    override get

  private constructor() /* primary */ {
    super/*Any*/()
    /* <init>() */

  }

  override infix fun String.combine(other: String): String {
    return <this>.plus(other = other)
  }

}

fun box(): String {
  with<IntMonoid, Int>(receiver = IntMonoid, block = local fun IntMonoid.<anonymous>(): Int {
    return listOf<Int>(elements = [1, 2, 3]).sum<Int>($context_receiver_0 = $this$with)
  }
) /*~> Unit */
  return with<StringMonoid, String>(receiver = StringMonoid, block = local fun StringMonoid.<anonymous>(): String {
    return listOf<String>(elements = ["O", "K"]).sum<String>($context_receiver_0 = $this$with)
  }
)
}

fun <T : Any?> List<T>.sum($context_receiver_0: Monoid<T>): T {
  return <this>.fold<T, T>(initial = $context_receiver_0.<get-unit>(), operation = local fun <anonymous>(acc: @ParameterName(name = "acc") T, e: T): T {
    return ($context_receiver_0, acc).combine(other = e)
  }
)
}