Exercise on clean shutdown

DoFoo.scala

import cats._
import cats.syntax.all._
import cats.effect._
import cats.effect.syntax.all._
import org.http4s._
import org.http4s.implicits._
import org.http4s.ember.server._
import scala.concurrent.duration._

object Main extends IOApp {

  def run(args: List[String]): IO[ExitCode] = {
    for {
      foo <- DoFoo.impl[IO]
      _ <- EmberServerBuilder.default[IO].withHttpApp(Routes.routes(foo).orNotFound).build
    } yield ()
  }.use(_ => IO.never)

}

object Routes {

  def routes[F[_]: Sync](doFoo: DoFoo[F]) = HttpRoutes.of[F]{
    case _ => doFoo.foo(Foo()).as(Response(Status.Accepted))
  }

}

case class Foo()

trait DoFoo[F[_]]{
  def foo(f: Foo): F[Unit]
}

object DoFoo {

  def impl[F[_]: Concurrent: Timer]: Resource[F, DoFoo[F]] = for {
    queue <- Resource.liftF(fs2.concurrent.Queue.noneTerminated[F, Foo])
    _ <- queue
      .dequeue
      .evalMap(foo => Timer[F].sleep(10.seconds) >> Concurrent[F].delay(println(foo)))
      .compile
      .drain
      .background
    _ <- Resource.make(Applicative[F].unit)(_ => queue.enqueue1(None))
  } yield new DoFoo[F]{
    def foo(f: Foo): F[Unit] = queue.enqueue1(f.some)
  }
  
}