Intersperse in Scala

intersperse.scala

implicit class SeqExtensions[A](val as: Seq[A]) extends AnyVal {

  def intersperse(a: A): Seq[A] = {
    val b = Seq.newBuilder[A]
    val it = as.iterator

    if (it.hasNext) {
      b += it.next()
      while(it.hasNext) {
        b += a
        b += it.next()
      }
    }

    b.result()
  }

}