nope.scala

// GUESS THE INFERRED TYPE FOR ys!

class :=[T,Q]
object := {
  /** Ignore default */
  implicit def useProvided[P, D] : P := D = new (P := D)
  /** Infer type argument to default */
  implicit def useDefault[D] : D := D = new (D := D)
}
object Test {
  def foo[T](implicit default: T := String, tag: scala.reflect.ClassTag[T]): T = null.asInstanceOf[T]
  def xs: Set[Int] = Set()
  def ys = xs + foo
}
// SPOILER SPACE










































// def xs: Set[Int]
// def ys: String