from the desk of brilliant paula bean

[juan_gandhi]

  implicit class StreamOfResults[T](source: Stream[Result[T]]) {
    def |>[U](op: T ⇒ Result[U]) = source map (t ⇒ t flatMap op)
    def filter(p: T ⇒ Outcome) = source |> (x => p(x) andThen Good(x))
    def map[U](f: T ⇒ U) = source map (_ map f)
  }

  implicit class StreamOfResults[T](source: Stream[Result[T]]) {
    def |>[U](op: T ⇒ Result[U]) = source map (t ⇒ t flatMap op)
    def filter(p: T ⇒ Result[_]) = source |> (x ⇒ p(x) returning x)
    def map[U](f: T ⇒ U) = source map (_ map f)
  }

E.g. use case:

  // this method could be written in a couple of lines, but it's better to keep the details
  def streamOfNewEobSelectors(): StreamOfResults[Element] = {
    // this function pairs an html element with its content
    def withContent(e: Element): Result[(Element, String)] = e.outerHtml() map ((e, _))

    // here we have a stream of elements paired with their content
    val pairs: StreamOfResults[(Element, String)] = streamOfEobElements |> withContent

    // here we filter the stream, leaving only the elements containing new stuff
    // note that the stuff we don't need is not kicked out, it's labeled as bad with an explanation
    val newOnes: StreamOfResults[(Element, String)]] = pairs filter (p => isNewClaim(p._2))

    // here we forget the html
    newOnes map {case p:(Element, String) => p._1}
  }

Note that filter does not take a boolean, it takes an Outcome, which is a logical value, from the logic that I'm trying to work on. It's not Boolean.