eta-expansion-implicits.scala

class TC[A](val x: String)

object TC {
  def getX[A: TC](a: A): String = implicitly[TC[A]].x

  implicit def anyTC[A]: TC[A] = new TC[A]("*")
  implicit val stringTC: TC[String] = new TC[String]("String")
}

object Example {
  val strings = List("a", "b")
  
  val ee1 = strings.map(TC.getX)
  val ee2 = strings.map(TC.getX _)
  val af1 = strings.map(TC.getX(_))
  val af2 = strings.map(s => TC.getX(s))
}

scala> Example.ee1
res0: List[String] = List(*, *)

scala> Example.ee2
res1: List[String] = List(*, *)

scala> Example.af1
res2: List[String] = List(String, String)

scala> Example.af2
res3: List[String] = List(String, String)

In the wild.