how to do nested loops in C -> Elegant Scheme

gistfile1.scm

;; I can't seem to convert this neat little
;; C code into elegant Scheme:
;;
;; // I didn't test this:
;; int c[20][20]
;; for (int x = -10 ; x < 10 ; x++)
;;   for (int y = -10 ; y < 10 ; y++)
;;     c[x+10][y+10] = x + y;

;; This is the best I've got so far:
(map (lambda (y)
       (map  (lambda (x) (+ x y))
             (iota 20 -10)))
     (iota 20 -10))

Are there any srfi's which will let me do something like:

(map-ranges ((-10 10)
             (-10 10))
            (lambda (x y) (+ x y)))

Or this:

(matrix-map (lambda (x y) (+ x y)
      (matrix-iota 20 -10 1 20 -10 1)