A macro for multi assign

multi-assign.scm

(define-syntax sets!
  (syntax-rules ()
    ((_ (var) (val))
     (set! var val))
    ((_ (var vars* ...) (val vals* ...))
     (let ((var0 val))
       (sets! (vars* ...) (vals* ...))
       (set! var var0)))))

(define a)
(define b)
(define c)
(sets! (a b c) (1 2 3))
;; a=1, b=2, c=3

(sets! (a b c) (c b a))
;; a=3, b=2, c=1