+(defmacro gnus-mapcar (function seq1 &rest seqs2_n)
+ "Apply FUNCTION to each element of the sequences, and make a list of the results.
+If there are several sequences, FUNCTION is called with that many arguments,
+and mapping stops as soon as the shortest sequence runs out. With just one
+sequence, this is like `mapcar'. With several, it is like the Common Lisp
+`mapcar' function extended to arbitrary sequence types."
+
+ (if seqs2_n
+ (let* ((seqs (cons seq1 seqs2_n))
+ (cnt 0)
+ (heads (mapcar (lambda (seq)
+ (make-symbol (concat "head"
+ (int-to-string
+ (setq cnt (1+ cnt))))))
+ seqs))
+ (result (make-symbol "result"))
+ (result-tail (make-symbol "result-tail")))
+ `(let* ,(let* ((bindings (cons nil nil))
+ (heads heads))
+ (nconc bindings (list (list result '(cons nil nil))))
+ (nconc bindings (list (list result-tail result)))
+ (while heads
+ (nconc bindings (list (list (pop heads) (pop seqs)))))
+ (cdr bindings))
+ (while (and ,@heads)
+ (setcdr ,result-tail (cons (funcall ,function
+ ,@(mapcar (lambda (h) (list 'car h))
+ heads))
+ nil))
+ (setq ,result-tail (cdr ,result-tail)
+ ,@(apply 'nconc (mapcar (lambda (h) (list h (list 'cdr h))) heads))))
+ (cdr ,result)))
+ `(mapcar ,function ,seq1)))
+