(mac fwiths (defs . body)
    `(with ,(intersperse-nils (keep-odd-pos defs))
           ,@(make-setters defs)
           ,@body))

  (def keep-odd-pos (lst)
    (if lst (cons (car lst) (keep-odd-pos (cddr lst)))))

  (def intersperse-nils (lst)
    (if lst (cons (car lst) (cons nil (intersperse-nils (cdr   lst))))))

  (def make-setters (lst)
    (if lst (cons (list '= (car lst) (cadr lst)) (make-setters (cddr lst)))))