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dependency injection sample with ZIO
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import scalaz.zio.{DefaultRuntime, IO, ZIO} | |
// domain layer ----------------------------------------------------------- | |
sealed trait AppError | |
case object NoValue extends AppError | |
case class Movie(id: Int, title: String) | |
trait MovieRepo { | |
def getMovie(id: Int): IO[AppError, Movie] | |
} | |
// application layer ---------------------------------------------- | |
val db = Map[Int, Movie](42 -> Movie(42, "A Movie")) | |
object MovieRepoImpl extends MovieRepo { | |
def getMovie(id: Int): IO[AppError, Movie] = | |
IO.fromEither(db.get(id).toRight(NoValue)) | |
} | |
trait Env { | |
val movieRepo: MovieRepo | |
} | |
object Env extends Env { | |
val movieRepo = MovieRepoImpl | |
} | |
object MovieService { | |
def getMovie(id: Int): ZIO[Env, AppError, Movie] = | |
ZIO.environment[Env] >>= (_.movieRepo.getMovie(id)) | |
} | |
val program: ZIO[Env, AppError, Movie] = MovieService.getMovie(42) | |
// runtime layer ------------------------------------------------- | |
new DefaultRuntime {}.unsafeRunSync(program.provide(Env)) | |
// testing layer ------------------------------------------------- | |
import cats.syntax.either._ | |
new DefaultRuntime {}.unsafeRunSync(program.provide(new Env { | |
val movieRepo = _ => IO.fromEither(NoValue.asLeft) | |
})) |
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