A module based encoding of Map which keeps the ordering associated with the Map. Then we can talk about `mymod.Map` as a type, knowing that `mymod.ordering` is the ordering.

map_module.scala

abstract class MapModule {
  type K
  def ordering: Ordering[K]
  type Map[_]
  
  def empty[V]: Map[V]
  def updated[V](m: Map[V], key: K, v: V): Map[V]
  def get[V](m: Map[V], key: K): Option[V]
  def items[V](m: Map[V]): Stream[(K, V)]
  def remove[V](m: Map[V], key: K): Map[V]
}