pulling out types?

whywrong.scala

class Test {
    def pullOutType[V](f:Map[String, V] => Unit) {
        var map = Map[String, V]()
        val params = Map("string" -> "string", "int" -> 20, "list" -> List("ok", "then"))

        params.foreach {
            case (field, value) => value match {
                case v:V => map = map + (field -> v)
                case _ => null
            }
            case _ => null
        }

        f(map)
    }
}

val x = new Test

x.pullOutType[List[String]] { data:Map[String, List[String]] =>
    assert(data.size == 2)
}

x.pullOutType { data:Map[String, String] =>
    assert(data.first == "string")
}

x.pullOutType { data:Map[String, Int] =>
    assert(data.first == 20)
}