loadNumberOfItemsFunctional.scala

def loadNumberOfItems(url: String): IO[Either[Exception, Int]] = {
  val maybeUrl: Option[Url] =
    Url(url)
  val eitherUrl: Either[Exception, Url] =
    maybeUrl.toRight(InvalidUrl)
  val eitherJson: Either[Exception, IO[Json]] =
    eitherUrl.map(u => request(u))
  val eitherResult: Either[Exception, IO[Either[Exception, Int]]] =
    eitherJson.map(futureJson =>
      futureJson.map(json => json.getFieldOption("number").flatMap(x => x.as[Int]).toRight(InvalidJson)))
  val eitherResult: IO[Either[Exception, Either[Exception, Int]]] =
    eitherResult.sequence
  eitherResult.map(_.flatten)
}