io-loop-usage.scala

import cats.effect._
import scala.concurrent.ExecutionContext.global

// needed to perform logical fork
implicit val cs = IO.contextShift(global)

// an infinite `flatMap` chain as the innerIO always return None
val myIO = retryIfNone(IO(None))

// perform a logical fork using `.start`, this to allow cancellation
val fiber: Fiber[IO, Int] = myIO.start.unsafeRunSync

// cancel the forked fiber
fiber.cancel.unsafeRunSync