import cats.effect.IO
import cats.effect.concurrent.Ref
import cats.data.State

import scala.util.Random

object Awesome extends App {

  case class Output(last: Option[String], count: Int)
  case class MyState(strings: List[String])
  object MyState {
    def init: MyState = MyState(List.empty[String])
  }

  val ref = Ref.of[IO, MyState](MyState.init).unsafeRunSync()

  def addWord(word: String): State[MyState, Output] = State[MyState, Output] { s =>
    s.copy(strings = s.strings :+ word) -> Output(s.strings.lastOption, s.strings.size)
  }

  def program: IO[Unit] =
    for {
      str <- IO(Random.nextString(10))
      out <- ref.modifyState(addWord(str))
      st  <- ref.get
      _   <- IO(println(s"Current Output $out"))
      _   <- IO(println(s"State $st"))
      _   <- program
    } yield ()

  program.unsafeRunSync()

}