IPSWAYS Scala Meetup - Creating unique Pairs of players using for expression

playerPairs.scala

val players = List("Timo", "Jan", "Lothar", "Sven", "Danny")
//> players  : List[String] = List(Timo, Jan, Lothar, Sven, Danny)
  
val playerPairs = for {
  p1 <- players
  p2 <- players
  if p1 != p2
} yield (p1, p2)                                
//> playerPairs  : List[(String, String)] = List((Timo,Jan), (Timo,Lothar), (Tim
//| o,Sven), (Timo,Danny), (Jan,Timo), (Jan,Lothar), (Jan,Sven), (Jan,Danny), (L
//| othar,Timo), (Lothar,Jan), (Lothar,Sven), (Lothar,Danny), (Sven,Timo), (Sven
//| ,Jan), (Sven,Lothar), (Sven,Danny), (Danny,Timo), (Danny,Jan), (Danny,Lothar
//| ), (Danny,Sven))

playerPairs.size                                
//> res0: Int = 20
  
val playerPairs2 = for {
  p1 <- players
  p2 <- players.dropWhile(_ != p1)
  if p1 != p2
} yield (p1, p2)                                
//> playerPairs2  : List[(String, String)] = List((Timo,Jan), (Timo,Lothar), (Ti
//| mo,Sven), (Timo,Danny), (Jan,Lothar), (Jan,Sven), (Jan,Danny), (Lothar,Sven)
//| , (Lothar,Danny), (Sven,Danny))

playerPairs2.size                               
//> res1: Int = 10