Why don't Scala Lists have an Ordering?

Question

Is there a reason why there is no implicit Ordering for Lists in Scala?

val lists = List(List(2, 3, 1), List(2, 1, 3))
lists.sorted

error: could not find im         


        

Answer 1

You can use sortWith. This doesn't take differently sized lists into account because zip will throw out the difference, but I think it does something like what you're after:

lists.sortWith((a,b) => {
  a.zip(b).filterNot(x => x._1 == x._2) match {
    case Nil => true
    case t => t._1 < t._2
  }
})