Scala 2.10 TypeTag usage

Question

I\'m digging new scala reflection api and can\'t figure out why the following snippet doesn\'t work as expected. Given hierarchy (tried to simplify as much as I can):

Answer 1

Just for fun:

import scala.reflect._
import scala.reflect.runtime.{currentMirror=>cm,universe=>ru}
import ru._

object Test extends App {
  type MyTag[A] = TypeTag[A]
  //type MyTag[A] = ClassTag[A]

  trait TF[A] {
    implicit def t: MyTag[A]

    def f[T <: A: MyTag]: PartialFunction[Any, A] = {
      //case msg: T => msg            // ok for ClassTag
      case msg: T @unchecked if matching[T](msg) => msg
      //case msg: T if typeOf[T] =:= typeOf[A] => msg
    }
    def matching[T](a: Any)(implicit tt: TypeTag[T]) =
      (cm reflect a).symbol.toType weak_<:< tt.tpe
  }

  case class TFilter[A: MyTag]() extends TF[A] {
    def t = implicitly[MyTag[A]]
  }

  trait Foo { def x: Int }
  case class Bar(x: Int) extends Foo
  case class Baz(x: Int) extends Foo

  val messages = Seq(1, Bar(0), "hello", Baz(1))
  println(messages collect TFilter[Foo].f[Foo])
  println(messages collect TFilter[Foo].f[Bar])
}