Try vs Either

Either.scala

// 1: Handler
def handle(req: Request): Response = {
  val indexes = req.get("indexes")
  service(indexes)
    .map(Response(json(_)))
    .orElse(Response.badRequest)
}


// 2: Service
def apply(indexes: Seq[Int]) = {
  for {
    index <- indexes
  } yield getDataAtIndex(index) match {
    case Right(result) => Right(process(result))
    case Left(ex) => Left(ex)
  }
}

def process(data: Int): Result = Result(data)

// 3: Low-level API
def getDataAtIndex(index: Int) = {
  index match {
    case 0 => Left(new Exception("not be zero"))
    case > 10 => Left(new Exception("not be 10"))
    case i => Right(identity(i))
  }
}

Try.scala

// 1: Handler
def handle(req: Request): Response = {
  val indexes = req.get("indexes")
  service(indexes)
    .map(Response(json(_)))
    .orElse(Response.badRequest)
}


// 2: Service
def apply(indexes: Seq[Int]) = {
  for {
    index <- indexes
    data <- getDataAtIndex(index)
  } yield process(data)
}



def process(data: Int): Result = Result(data)

// 3: Low-level API
def getDataAtIndex(index: Int) = Try {
  index match {
    case 0 => throw new Exception("not be zero")
    case > 10 => throw new Exception("not be 10")
    case i => identity(i)
  }
}