pipeline

simple_pipeline.scala

package me.lavando.user.api.features

import scala.concurrent.duration._
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.{Await, Future}
import scala.util.Failure

/**
  * @author Gabriel Francisco <[email protected]>
  */
object Example extends App{
  implicit class NiceArrow[A, B](func: (Future[A] => Future[B])) {
    def ~>[C](f: Future[B] => Future[C]): (Future[A]) => Future[C] = func andThen f
    def run(eventualA: Future[A]): Future[B] = func(eventualA)
  }

  implicit class FutureHandler[A](result: Future[A]) {
    def handling[E <: Exception](t: E => Unit): Future[A] = {
      result.onComplete {
        case Failure(e: E) => t(e)
        case _ =>
      }

      result
    }
  }

  def mapToInt: Future[String] => Future[Int] = str => str map { s => s.toInt }
  def sumTwo: Future[Int] => Future[Int] = int => int map { i => i + 2 }
  def multiplyThree: Future[Int] => Future[Int] = int => int map { i => i * 3 }
//  def multiplyThree: Future[Int] => Future[Int] = int => int map { i => i / 0 }
  def showResultAsMessage: Future[Int] => Future[String] = int => int map { i => s"the result is equal to $i" }

  val pipeline = mapToInt ~> sumTwo ~> multiplyThree ~> showResultAsMessage

  val result =
    pipeline
      .run(Future { "2" })
      .handling { (e: ArithmeticException) => println("ups...") }
      .handling { (e: IllegalArgumentException) => println("ups...") }

  println(Await.result(result, 2 seconds))
}