refined-literal-scala3.scala

import scala.compiletime.ops.{any, int}

trait Odd
object Odd {
  type IsOdd[I <: Int] = any.!=[int.%[I, 2], 0]

  def apply[I <: Int](i: I)(using IsOdd[I] =:= true): Int & Odd =
    i.asInstanceOf[Int & Odd]
}

trait Even
object Even {
  type IsEven[I <: Int] = any.==[int.%[I, 2], 0]

  def apply[I <: Int](i: I)(using IsEven[I] =:= true): Int & Even =
    i.asInstanceOf[Int & Even]
}

val i1 = Odd[1]
// val i2 = Odd[2] // compile error
// val i3 = Even[3] // compile error
val i4 = Even[4]