unfoldr in Scala

unfoldr.scala

def unfoldr[A, B](seed: B)(func: B => Option[(A, B)]): Stream[A] =
  func(seed) match {
     case Some((a, b)) => a #:: unfoldr(b)(func)
     case None => Stream.empty
  }

/*
* Infinite sequence:
*   val s = unfoldr (0) (b => Some(b,b+1))
* Fibonacci sequence:
*   val fibs = unfoldr ((BigInt(1),BigInt(1))) {b => Some(b._1, (b._2, b._1 + b._2))}
*/