srfi cond

cond.el

(defmacro srfi-cond (&rest clauses)
  (reduce
   (lambda (clause res)
     (let ((test (car clause)))
       (cond
        ((eq (cadr clause) '=>)
         (unless (= (length clause) 3)
           (error "Malformed `srfi-cond' test => expr"))
         (let ((v (make-symbol "v")))
           `(let ((,v ,test))
              (if ,v (,(caddr clause) ,v) ,res))))
        ((eq (caddr clause) '=>)        ; srfi-61
         (unless (= (length clause) 4)
           (error "Malformed `srfi-cond' test guard => expr"))
         (let ((v1 (make-symbol "v1")))
           `(let ((,v1 ,test))
              (if (and ,v1 (,(cadr clause) ,v1))
                  (,(cadddr clause) ,v1)
                ,res))))
        (t
         `(if ,test 
              (progn ,@(cdr clause))
            ,res)))))
   clauses
   :from-end t
   :initial-value nil))