functional programming - zipWith (mapping over multiple Seq) in Scala

Question

Suppose I have

val foo : Seq[Double] = ...
val bar : Seq[Double] = ...

and I wish to produce a seq where the baz(i) = foo(i) + bar(i). One way I can think of to do this is

val baz : Seq[Double] = (foo.toList zip bar.toList) map ((f: Double, b : Double) => f+b)

However, this feels both ugly and inefficient -- I have to convert both seqs to lists (which explodes with lazy lists), create this temporary list of tuples, only to map over it and let it be GCed. Maybe streams solve the lazy problem, but in any case, this feels like unnecessarily ugly. In lisp, the map function would map over multiple sequences. I would write

(mapcar (lambda (f b) (+ f b)) foo bar)

And no temporary lists would get created anywhere. Is there a map-over-multiple-lists function in Scala, or is zip combined with destructuring really the 'right' way to do this?

Answer 1

In Scala 2.8:

val baz = (foo, bar).zipped map (_ + _)

And it works for more than two operands in the same way. I.e. you could then follow this up with:

(foo, bar, baz).zipped map (_ * _ * _)