ZioProvideDemo.scala

ZioProvideDemo.scala

import zio._
import zio.console._

object ZioProvideDemo extends App {

  trait HelloService {
    val helloService: HelloService.Service
  }

  object HelloService {
    trait Service {
      def hello(name: String): RIO[Console, Unit]
    }
  }

  trait HelloServiceLive extends HelloService {
    val helloService: HelloService.Service = new HelloService.Service {
      override def hello(name: String): RIO[Console, Unit] = putStrLn(s"Hello $name!")
    }
  }

  def doSomeStuffDependsOnHelloService(): ZIO[HelloService with Console, Nothing, Int] =
    (for{
      _ <- putStrLn("Please enter your name.")
      name <- getStrLn
      _ <- ZIO.environment[HelloService].flatMap(_.helloService.hello(name))
    } yield 0).fold(_ => 1, s => s)

  val program: ZIO[HelloService with Console, Nothing, Int] = doSomeStuffDependsOnHelloService()

  object HelloRuntimeLive extends HelloServiceLive with Console.Live

  val hwRuntime: HelloService with Console = HelloRuntimeLive

  override def run(args: List[String]): ZIO[zio.ZEnv, Nothing, Int] =
    program.provide(hwRuntime) *> putStrLn("Done.").map(_ => 0)

}