Scala类型限定

 package big.data.analyse.scala

 /**
   * 类型限定
   * Created by zhen on 2018/12/9.
   */
 object Lxxd {
   def main(args: Array[String]) {
     // A =:= B 表示A,B类型相同
     def it_is_equal[T](i:T)(implicit ev : T =:= Int){
       println("life is short, you need python...")
     }
     it_is_equal(21)
     // it_is_equal("python") //Error:(14, 16) Cannot prove that String =:= Int.
     // A <:< B 表示A类型是B类型的子类型
     def it_is_more[T](i:T)(implicit ev : T <:< java.io.Serializable){
       println("life is short, you need spark...")
     }
     // it_is_more(12) // Error:(19, 15) Cannot prove that Int <:< java.io.Serializable.
     it_is_more("spark")
   }
 }

结果：