Compact way that searches multiple alists

Question

I have a collection of alists, ptc-1 through ptc-5. Would it be possible to make the following code more compact, rather having to add more sections if there are more alists?

(let ( (v "") )

  (setq v (cdr (assoc word ptc-1)))
  (unless (null v)
     (add-to-list 'ptc
         (replace-regexp-in-string word v word)))

  (setq v (cdr (assoc word alist-2)))
  (unless (null v)
     (add-to-list 'ptc
         (replace-regexp-in-string word v word)))
  
  (setq v (cdr (assoc word alist-3)))
  (unless (null v)
     (add-to-list 'ptc
         (replace-regexp-in-string word v word)))

  (setq v (cdr (assoc word alist-4)))
  (unless (null v)
     (add-to-list 'ptc
         (replace-regexp-in-string word v word)))

  (setq v (cdr (assoc word alist-5)))
  (unless (null v)
     (add-to-list 'ptc
         (replace-regexp-in-string word v word))) )

Answer 1

You should be able to loop over each of the alists with a dolist loop macro. So something like:

(let ((v ""))
  (dolist (alist (list ptc-1 ptc-2 ptc-3 ptc-4 ptc-5))
    (setq v (cdr (assoc word alist)))
    (unless (null v)
       (add-to-list 'ptc
           (replace-regexp-in-string word v word)))
  v)

For a shorter example, (dolist (x '(64 65 66)) (insert x)) would insert ABC into the current buffer.

I also took the liberty of assuming the list of alists contained ptc-1 through ptc-5, unlike your example above which used alist-2 through alist-5.

However, just as a suggestion, if you are iterating over multiple alists like this, it might help to think of one data structure that you could operate on instead of 5 different parallel structures. I don't have a sense of the problem space here so I can't make any suggestions, but might be something worth considering.