Main2.scala

/**
  * Created by renkai on 16/9/7.
  */
object Main2 {

  def isSingleton[A](a: A)(implicit ev: A <:< Singleton = null) = {
    Option(ev).isDefined
  }

  def isSingleton2[A](a: A) = {
    isSingleton(a)
  }

  def isSingleton3[A](a: A)(implicit ev: A <:< Singleton = null) = {
    isSingleton(a)
  }

  def main(args: Array[String]): Unit = {
    println("isSingleton(Main2) = " + isSingleton(Main2))
    println("isSingleton2(Main2) = " + isSingleton2(Main2))
    println("isSingleton3(Main2) = " + isSingleton3(Main2))

//    isSingleton(Main2) = true
//    isSingleton2(Main2) = false
//    isSingleton3(Main2) = true
  }
}