Demonstrate cancellable tasks are cancelled while they are sleeping

CancellableTask.scala

package org.teckhooi.dojo3.concurrent

import cats.effect.{IO, IOApp}

import scala.concurrent.duration.*

object CancellableTask extends IOApp.Simple {
  def task(i: Int, d: Duration): IO[Unit] = IO.sleep(d) *> IO.println(s"Task $i completed")

  override def run: IO[Unit] = for {
    f <- IO.uncancelable(poll => poll(task(1, 2.second)) *> task(2, 1500.millis) *> poll(task(3, 2.second))).start
    _ <- IO.sleep(3.seconds) *> f.cancel
  } yield ()
}