TwitterServer-And-CatsEffect

IOTwitterServer.scala

import cats.effect.{ContextShift, IO, Resource, Timer}
import com.twitter.finagle.{Http, ListeningServer, Service}
import com.twitter.finagle.http.{Request, Response}
import com.twitter.server.TwitterServer
import com.twitter.util.Future
import io.finch.Endpoint
import io.finch.internal.ToEffect
import java.util.concurrent.CountDownLatch
import scala.concurrent.ExecutionContext

object Main extends TwitterServer {

  protected implicit def contextShift: ContextShift[IO] =
    IO.contextShift(ExecutionContext.global)

  protected implicit def timer: Timer[IO] =
    IO.timer(ExecutionContext.global)

  final def main(): Unit = {
    val latch = new CountDownLatch(1)
    val cancel = run().unsafeRunCancelable {
      case Right(_) => latch.countDown()
      case Left(e) => exitOnError(e)
    }

    onExit {
      cancel.unsafeRunSync()
      latch.countDown()
    }

    latch.await()
  }

  def run(): IO[Unit] = {
    def closeLater(l: ListeningServer): IO[Unit] =
      IO.suspend(implicitly[ToEffect[Future, IO]].apply(l.close()))

    def serve(s: Service[Request, Response]): Resource[IO, ListeningServer] =
      Resource.make[IO, ListeningServer](
        IO(Http.server.withStatsReceiver(statsReceiver).serve(":8081", s))
      )(closeLater)
    
    for {
      _ <- IO(println("starting"))
      _ <- serve(Endpoint[IO].const("Hello").toService[Text.Plain]).use(_ => IO.never)
    } yield ()
  }
}

First of all, thanks for the example. However, I noticed that ToEffect is changed to ToAsync. Can you create a new revision?