scala: yield pairwise combinations of two loops

Question

I would like to create a collection with tuples containing all pairwise combinations of two lists. Something like:

for ( x <- xs )
  for ( y <- ys ) 
    yield (x,y)

In Python this would work, in Scala apparently for yields only for the last loop (so this evaluates to Unit)

What is the cleanest way to implement it in Scala?

Answer 1

You were almost there:

scala> val xs = List (1,2,3)
xs: List[Int] = List(1, 2, 3)

scala> val ys = List (4,5,6)
ys: List[Int] = List(4, 5, 6)

scala> for (x <- xs; y <- ys) yield (x,y)
res3: List[(Int, Int)] = List((1,4), (1,5), (1,6), (2,4), (2,5), (2,6), (3,4), (3,5), (3,6))