Scala - can yield be used multiple times with a for loop?

Question

An example:

val l = List(1,2,3)
val t = List(-1,-2,-3)

Can I do something like this?

for (i <- 0 to 10) yield (l(i)) yie         


        

Answer 1

Here is a type-agnostic solution for an unknown, varying number of elements in a unknown number of lists:

def xproduct (xx: List [List[_]]) : List [List[_]] = 
  xx match {
    case aa :: bb :: Nil => 
      aa.map (a => bb.map (b => List (a, b))).flatten       
    case aa :: bb :: cc => 
      xproduct (bb :: cc).map (li => aa.map (a => a :: li)).flatten
    case _ => xx
}

For 2 Lists it is overengineered. You could although call it

   xproduct (List (l, t))