List.unfold(0){ a => if (a < 10) Some(a + 1, a.toString) else None}

collection-unfold.scala

import scala.collection.generic._

object RichTraversableCompanion {
  implicit def pimp[CC[X] <: Traversable[X] with GenericTraversableTemplate[X, CC], T](comp: TraversableFactory[CC]) = new RichTraversableCompanion[CC](comp)
}

class RichTraversableCompanion[CC[X] <: Traversable[X] with GenericTraversableTemplate[X, CC]](comp: TraversableFactory[CC]) {
  def unfold[A, B](seed: A)(f: A => Option[(A, B)]): CC[B] = {
    val builder = comp.newBuilder[B]
    @annotation.tailrec
    def loop(a: A): Unit = f(a) match {
      case Some((a, b)) => builder += b; loop(a)
      case None =>
    }
    loop(seed)
    builder.result
  }

  def iterateWhile[A](seed: A)(f: A => Option[A]): CC[A] = {
    val builder = comp.newBuilder[A]
    @annotation.tailrec
    def loop(a: A): Unit = f(a) match {
      case Some(a) => builder += a; loop(a)
      case None =>
    }
    loop(seed)
    builder.result
  }
}

import RichTraversableCompanion._

List.unfold(0) {a => if (a < 10) Some(a + 1, a.toString) else None}
Stream.unfold(0) {a => if (a < 10) Some(a + 1, a.toString) else None}
Vector.unfold(0) {a => if (a < 10) Some(a + 1, a.toString) else None}
Vector.iterateWhile(0) {a => if (a < 10) Some(a + 1) else None}