TPayne's problem from http://dpaste.com/1325681/

gistfile1.scala

object TPayne extends App {

  val m = Map(
    "2" -> List(List("1")),
    "3" -> List(List("9"), List("5", "6", "7", "8")),
    "1" -> List(List("8", "9"), List("2"), List("2", "3")))

  def combos[A, B](xs: Map[A, List[B]]): List[Map[A, B]] =
    (List(Map[A, B]()) /: xs)((m, p) => p._2.flatMap(v => m.map(_ + (p._1 -> v))))

  combos(m).foreach(println)

//  Map(2 -> List(1), 3 -> List(9), 1 -> List(8, 9))
//  Map(2 -> List(1), 3 -> List(5, 6, 7, 8), 1 -> List(8, 9))
//  Map(2 -> List(1), 3 -> List(9), 1 -> List(2))
//  Map(2 -> List(1), 3 -> List(5, 6, 7, 8), 1 -> List(2))
//  Map(2 -> List(1), 3 -> List(9), 1 -> List(2, 3))
//  Map(2 -> List(1), 3 -> List(5, 6, 7, 8), 1 -> List(2, 3))

}