longliveenduro

public interface ArticleService {
  ArticleDetails getArticleDetails(Long articleId) throws ArticleNotFoundException;
}

longliveenduro

trait ArticleService {
  def getArticleDetails(articleId: Long): ArticleDetails 
}

longliveenduro

trait ArticleService {
  def getArticleDetails(articleId: Long): Either[ArticleNotFound, ArticleDetails]
}

longliveenduro

trait ArticleService {
  def getArticleDetails(articleId: Long): Future[Either[ArticleNotFound, ArticleDetails]]
}

longliveenduro

case object ArticleNotFound

trait ArticleService {
  def getArticleDetails(articleId: Long): Future[Either[ArticleNotFound.type, ArticleDetails]]
  def getArticleIdByUniqueName(articleName: String): Future[Either[ArticleNotFound.type, Long]]
}

longliveenduro

def getArticleDetails(articleName: String): Future[Either[ArticleNotFound.type, ArticleDetails]] = {
  for {
    articleId <- articleService.getArticleIdByUniqueName(articleName).right
    article <- articleService.getArticleDetails(articleId).right
  } yield article
}

longliveenduro

  case object ArticleNotFound

  trait ArticleService {
    def getArticleDetails(articleId: Long): Future[\/[ArticleNotFound.type, ArticleDetails]]
    def getArticleIdByUniqueName(articleName: String): Future[\/[ArticleNotFound.type, Long]]
  }

  def getArticleDetails(articleName: String): Future[\/[ArticleNotFound.type, ArticleDetails]] = {
    for {
      articleId <- articleService.getArticleIdByUniqueName(articleName)

longliveenduro

  implicit val FutureFunctor = new Functor[Future] {
    def map[A, B](a: Future[A])(f: A => B): Future[B] = a map f
  }

  implicit val FutureMonad = new Monad[Future] {
    def point[A](a: => A): Future[A] = Future(a)
    def bind[A, B](fa: Future[A])(f: (A) => Future[B]): Future[B] = fa flatMap f
  }

longliveenduro

  def getArticleDetails(articleName: String): Future[\/[ArticleNotFound.type, ArticleDetails]] = {
    val r = for {
      articleId <- EitherT(articleService.getArticleIdByUniqueName(articleName))
      article <- EitherT(articleService.getArticleDetails(articleId))
    } yield article
    r.run
  }

longliveenduro

import com.twitter.util.Future
import scalaz.{EitherT, Monad, Functor, \/}


object EitherTest {

  val articleService = new ArticleService {
    def getArticleDetails(articleId: Long): Future[\/[ArticleNotFound.type, ArticleDetails]] = ???
    def getArticleIdByUniqueName(articleName: String): Future[\/[ArticleNotFound.type, Long]] = ???
  }