UserRepository Example

gistfile1.txt

  import scala.collection.mutable
  import scala.concurrent.ExecutionContext.Implicits.global
  import scala.concurrent.{Await, Future}
  import scala.concurrent.duration.Duration

  case class User(id: Long, name: String)

  @free trait UserRepository[F[_]] {
    def get(id: Long): FreeS[F, Option[User]]

    def save(user: Option[User]): FreeS[F, Option[User]]

    def getAll(filter: String): FreeS[F, List[User]]
  }

  implicit val userHandler = new UserRepository.Handler[Future] {
    val users = mutable.ListBuffer(User(1, "user1"), User(2, "user2"), User(3, "user3"))

    def get(id: Long): Future[Option[User]] = Future.successful(users.find(_.id == id))

    def save(user: Option[User]): Future[Option[User]] = Future {
      user.foreach { u => users += u }
      user
    }

    def getAll(filter: String): Future[List[User]] = Future.successful(users.find(_.name.contains(filter)).toList)
  }

  def program[F[_]](implicit A: UserRepository[F]) = {
    import A._
    for {
      userInput <- get(12)
      _ <- save(userInput)
      users <- getAll("user1")
    } yield ()
  }

  val futureValue = program[UserRepository.Op].exec[Future]
  Await.result(futureValue, Duration.Inf)