import scala.reflect.mirror._ object Test extends App { class C[T >: Null] { val code = reify{ val tt = implicitly[TypeTag[T]] println("mah typetag is: %s".format(tt)) } println(freeTypes(code)) val T = freeTypes(code)(0) mkToolBox().runExpr(code, Map(T -> definitions.StringClass.asType)) } new C[String] }