ZIO workshop

MiniTest.scala

package com.upstartcommerce.rating


import zio.ZIO
import zio.console.Console

object MiniTest extends zio.App {

  trait GetUser {
    def user: User
  }

  case class User(name: String)

  type Environment = Console with GetUser

  val printAAA: ZIO[Console, Throwable, Unit] =
    ZIO.accessM[Console](_.console.putStrLn("AAA"))


  def printUser(u: User): ZIO[Console, Throwable, Unit] =
    ZIO.accessM[Console](_.console.putStrLn(u.name))

  val printUserZIO: ZIO[Environment, Throwable, Unit] =
    ZIO.accessM[Environment](
      e => e.console.putStrLn(e.user.name))

  override def run(args: List[String]): ZIO[zio.ZEnv, Nothing, Int] =
    (for {
      _ <- printAAA
      _ <- printUser(User("Gordon"))
      _ <- printUserZIO

    } yield ()).provideSome[zio.ZEnv](
      env => new Console with GetUser  {
        override val console: Console.Service[Any] = env.console
        override def user: User = User("Yan")
      }
    ).orDie as 0
}

ZioDependencies.scala

import zio.{RIO, Task}

object ZioDependencies {

  /************* AUTH *************/
  trait Auth {
    def auth: Auth.Service
  }

  object Auth {
    trait Service {
      def token: Task[String]
    }

    // this is useful so I do not need to repeat myself in provide
    trait HeaderAuth extends Auth {
      override def auth: Service = HeaderAuthService
    }

    object HeaderAuthService extends Service {
      override def token: Task[String] = ???
    }
  }

  /************* Storage *************/
  trait Storage[R] {
    def storage: Storage.Service[R]
  }

  object Storage {
    trait Service[R] {
      def get(id: Int): RIO[R, String]
    }
  }

  object LiveStorage extends Storage.Service[Auth] {
    override def get(id: Int): RIO[Auth, String] = ???
  }

  object TestStorage extends Storage.Service[Any] {
    override def get(id: Int): RIO[Any, String] = ???
  }

  /************* ExternalSystem *************/
  trait ExternalSystem {
    // here must be all deps
    def externalSystem: ExternalSystem.Service[Auth]
  }

  object ExternalSystem {
    trait Service[-R] {
      def get(id: Int): RIO[R, String]
    }
  }

  object LiveExternalSystem extends ExternalSystem.Service[Auth] {
    override def get(id: Int): RIO[Auth, String] = ???
  }

  object TestExternalSystem extends ExternalSystem.Service[Any] {
    override def get(id: Int): RIO[Any, String] = ???
  }

  /************* Prod dependencies *************/
  
  val prodZio: RIO[Auth with Storage[Auth] with ExternalSystem, Int] = ???
  
  prodZio.provide(
    new Auth with Storage[Auth] with ExternalSystem {
      override def auth: Auth.Service = Auth.HeaderAuthService
      override def storage: Storage.Service[Auth] = LiveStorage
      override def externalSystem: ExternalSystem.Service[Auth] = LiveExternalSystem
    }
  )

  prodZio.provide(
    new Storage[Auth] with ExternalSystem with Auth.HeaderAuth {
      override def storage: Storage.Service[Auth] = LiveStorage
      override def externalSystem: ExternalSystem.Service[Auth] = LiveExternalSystem
    }
  )

  /************* Test dependencies *************/

  val testZio: RIO[Auth with Storage[Any] with ExternalSystem, Int] = ???
  
  testZio.provide(
    new Auth with Storage[Any] with ExternalSystem {
      override def auth: Auth.Service = Auth.HeaderAuthService
      override def storage: Storage.Service[Any] = TestStorage
      override def externalSystem: ExternalSystem.Service[Auth] = TestExternalSystem
    }
  )
}