foo.scala

def save[A](key: String)(f: CouchValueHandler[A])(implicit formatter: CouchFormat[A], context: CouchContext): Future[A] =
  get[A](key).flatMap {
    case Some(row) =>
      update[A](key, row)(value => f(value.some))
    case None      =>
      val value = f(None)
      add(key, value) flatMap {
        case false => // Failure to add means there is now a value, start the process over.
          save(key)(f)
        case true  =>
          Future.successful(value)
      }
  }