cofree impl of fib

fib.scala

final case class Cofree[F[_], A](head: A, tail: F[Cofree[F,A]])

val fibs: Cofree[Eval, Int] = {
  def unfold(p1: Int, p2: Int): Cofree[Eval, Int] =
    Cofree(p1 + p2, Eval.later(unfold(p2, p1 + p2)))

  unfold(0, 1)
}

scala> fibs.head
res0: Int = 1

scala> fibs.tail.value
res3: Cofree[cats.Eval,Int] = Cofree(2,cats.Later@14cae9bc)

scala> fibs.tail.value.tail.value
res5: Cofree[cats.Eval,Int] = Cofree(3,cats.Later@4a46ec2a)

scala> fibs.tail.value.tail.value.tail.value
res6: Cofree[cats.Eval,Int] = Cofree(5,cats.Later@5e0774f7)