Getting return types of methods without actually calling them

type-test.scala

  import scala.reflect.{ classTag, ClassTag }

  trait X {
    def f: Seq[Int]
  }

  trait Getter[T] {
    def apply[U: ClassTag, C[_]](f: T ⇒ C[U]): ClassTag[U] = implicitly[ClassTag[U]]
  }
  object Getter extends Getter[Any]

  def memberClassTagFrom[T]: Getter[T] = Getter.asInstanceOf[Getter[T]]

  println(memberClassTagFrom[X](_.f))