TypeTag sometimes prints qualified names, and other times not.

typetag.scala

scala> import scala.reflect.runtime.universe._
import scala.reflect.runtime.universe._

scala> typeTag[List[Double]]
res0: reflect.runtime.universe.TypeTag[List[Double]] = TypeTag[scala.List[Double]]

scala> typeTag[List[Double]].tpe.toString
res1: String = scala.List[Double]

scala> def foo[A,B](f: A => B)(implicit T: TypeTag[B]) = T.tpe.toString
foo: [A, B](f: A => B)(implicit T: reflect.runtime.universe.TypeTag[B])String

scala> foo((i: Double) => List(i))
res2: String = List[Double] // why is this just 'List[Double]', while typeTag[List[Double]] prints as `scala.List[Double]`?

scala> foo((i: Double) => scala.List(i): scala.List[Double])
res4: String = scala.List[Double] // ??

Related, it looks like TypeTag does not do anything with type aliases.