I've defined a function that is supposed to iterate over an alist, and use the CAR and CDR of each element in the list to populate the regexp in re-search-forward and the replacement string in replace-match, respectively. Here is what I have:

(defun search-and-replace ()
  (let ((alist '(("regexp" "replacement-str")
    (dolist (search-pair alist)
      (while (re-search-forward (car search-pair) nil t)
        (replace-match (cdr search-pair))))))

This returns an error: Wrong type argument: stringp, ("replacement-str"). What am I missing?


Thanks for the help. Here's what I ended up with:

(defun search-and-replace (alist)
    (goto-char (point-min))
    (dolist (search-pair alist)
      (while (re-search-forward (car search-pair) nil t)
        (replace-match (cdr search-pair)))
      (goto-char (point-min))))

Where each item in ALIST is a cons cell of ("regexp" . "replacement-string").

  • 1
    @rjww I don't think YoungFrog was talking down to you, I see only helpful comments. Perhaps you read some sarcasm into it, but I don't think any was intended.
    – npostavs
    Jan 14, 2017 at 6:07
  • @YoungFrog I must have misread the tone, sorry everyone.
    – rjww
    Jan 14, 2017 at 6:48
  • @rjww I guess I missed some now-deleted comments, but I confirm what npostavs said. I like reading comments that are short and go straight to the point, so I try to write them that way too ; sorry if it sounded harsh. Nothing personal of course.
    – YoungFrog
    Jan 15, 2017 at 11:26
  • @YoungFrog No it was my fault. Thanks very much for your help, I appreciate it.
    – rjww
    Jan 15, 2017 at 12:26

1 Answer 1


You want (cadr search-pair), not (cdr search-pair).

Either that or use an alist whose entries are dotted pairs, with the cdrs being your replacement strings.

The error message tells you that a string was expected and instead the list ("replacement-str") was passed.

  • Thanks, that did it. I actually meant to include them as dotted pairs, but conveniently messed it up in both the code and the example above.
    – rjww
    Jan 14, 2017 at 3:22

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