env_cats_interop_1.scala

object catz extends CatsInstance
abstract class CatsInstance {
  import zio.interop.catz._
  implicit def contextShift[Ctx]: ContextShift[Env[Ctx, ?]] = new EnvContextShift()
  implicit def timer[Ctx]: EnvTimer[Ctx] = new EnvTimer
}

class EnvTimer extends Timer[Env[Ctx, ?]] {
  import zio.interop.catz.implicits._
  override def clock: Clock[Env[Ctx, ?]] = {
    val timer = ioTimer[Throwable]
    val clock = timer.clock
    new Clock[Env[Ctx, ?]] {
      override def monotonic(unit: TimeUnit): Env[Ctx, Long] = ofZIO(clock.monotonic(unit))
      override def realTime(unit: TimeUnit): Env[Ctx, Long] = ofZIO(clock.realTime(unit))
    }
  }
  override def sleep(timespan: FiniteDuration): Env[Ctx, Unit] = ofZIO(timer.sleep(timespan))
}

class EnvContextShift[Ctx](implicit contextShift: ContextShift[RIO[Context[Ctx], ?]]) extends ContextShift[Env[Ctx, ?]] {
  override def shift: Env[Ctx, Unit] = ofZIO(contextShift.shift)
  override def evalOn[A](ec: ExecutionContext)(fa: Env[Ctx, A]): Env[Ctx, A] = ofZIO(contextShift.evalOn(ec)(fa.run))
}