Lame-o Queue to show how to implement new collections

queue.scala

package misc

import collection.SeqLike
import scala.collection.mutable.Builder
import scala.collection.mutable.ListBuffer
import scala.collection.generic.SeqFactory
import scala.collection.generic.GenericTraversableTemplate
import scala.collection.generic.CanBuildFrom

object Queue extends SeqFactory[Queue] {
  def newBuilder[A]: Builder[A, Queue[A]] = new ListBuffer[A] mapResult (new Queue(_))

  implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Queue[A]] = new GenericCanBuildFrom[A]
}

class Queue[+A] private (private val as: List[A]) extends Seq[A] with SeqLike[A, Queue[A]] with GenericTraversableTemplate[A, Queue] {

  override def companion = Queue
  def apply(i: Int): A = as(i)
  def length = as.length
  def iterator = as.iterator
}