相关疑难解决方法(0)

Scala生活中的一个可悲事实是,如果你实例化一个List [Int],你可以验证你的实例是一个List,你可以验证它的任何单个元素是一个Int,但不是它是一个List [ Int],可以很容易地验证:

scala> List(1,2,3) match {
     | case l : List[String] => println("A list of strings?!")
     | case _ => println("Ok")
     | }
warning: there were unchecked warnings; re-run with -unchecked for details
A list of strings?!

-unchecked选项将责任直接归咎于类型擦除:

scala>  List(1,2,3) match {
     |  case l : List[String] => println("A list of strings?!")
     |  case _ => println("Ok")
     |  }
<console>:6: warning: non variable type-argument String in type pattern is unchecked since it is eliminated by erasure
        case l …