type Comparison<in T> = {(T, T) : Int}

fun naturalOrder<in T : IComparable<T>>(a : T, b : T) : Int = a.compareTo(b)

fun castingNaturalOrder(a : Object, b : Object) : Int = a.as<Comparable<Object>>.compareTo(b.as<Comparable<Object>>)

enum class ComparisonResult {
  LS,EQ, GR
}

type MatchableComparison<in T> = {(T, T) : ComparisonResult}

fun asMatchableComparison<T>(cmp : Comparison<T>) : MatchableComparison<T> = {a, b =>
  val res = cmp(a, b)
  if (res == 0) return ComparisonResult.EQ
  if (res < 0) return ComparisonResult.LS
  return ComparisonResult.GR
}