Tuple2Zipped.Ops may not have intended to expose x: http://www.scala-lang.org/api/2.11.7/index.html#scala.Tuple2@x:(T1,T2) It's a race between Team Scala and the Puzzler Guy: https://github.com/scalapuzzlers/scalapuzzlers.github.com/pull/127#issuecomment-118545628