simple test main for ZIO Environment

SimpleMain.scala

import scalaz.zio.{App, IO, ZIO}
import scala.io.StdIn

//  "org.scalaz" %% "scalaz-zio" % "1.0-RC3"

object SimpleMain extends App {
  sealed trait AppError
  case object NoValue extends AppError

  def valueOf(key: String): ZIO[Map[String, String], AppError, String] =
    ZIO.accessM { env =>
      ZIO.fromEither(env.get(key).toRight(NoValue))
    }

  val program: ZIO[Map[String, String], AppError, Unit] = for {
    s <- IO.effectTotal(StdIn.readLine())
    v <- valueOf(s)
    _ <- IO.effectTotal(println(v))
  } yield ()

  def run(args: List[String]): ZIO[Environment, Nothing, Int] =
    program.provide(Map("42" -> "Foo")).fold(_ => 1, _ => 0)
}