object Test extends App {
  class Number(i: Int)
 
  object UnliftNumber {
    def unapply(t: Any): Option[Number] = t match {
      case i: Int => Some(new Number(i))
      case _ => None
    }
  }
 
  def eval(expr: Any): Option[Number] = expr match {
    case UnliftNumber(n) => Some(n)
    case _ => None
  }
 
  println(eval(1))
}

    /** If this is a case class, the case field accessors (which may be an empty list.)
     *  Otherwise, if there are any product selectors, that list.
     *  Otherwise, a list containing only the type itself.
     */
    def typesOfSelectorsOrSelf(tp: Type): List[Type] = (
      if (tp.typeSymbol.isCase)
        typesOfCaseAccessors(tp)
      else typesOfSelectors(tp) match {
        case Nil => tp :: Nil
        case tps => tps
      }
    )