How do you pattern match an empty Map?

Map doesn't provide any extractor with unapply()/unapplySeq() methods out of the box, so it is impossible to match key-value pairs it in pattern matching. But if you need only to match if map is empty you can:

val map = Map.empty[String, String]

val result = map match {
  case m:Map[String, String] if m.isEmpty =>  false
  case _ =>                                   true 
}

println(result)

outputs:

false