My current configuration of Emacs (24.5.1 on U15.10) has auto-suggest set up for find-file, that is, when I do C-x C-f, the mini-buffer fills with possible completions that I can tab to and hit enter to select. I'd like to do that on an interactive function I'm writing where it would auto-suggest each element of this list

((thing1a . thing1b) (thing2a . thing2b) ... )

Is there boilerplate code for this someone knows about?

  • Have you tried just using icomplete-mode? That presents completion candidates in the minibuffer, and you can choose any of them by hitting a key. C-h f icomplete-mode RET.
    – Drew
    Dec 3, 2015 at 17:51
  • 1
    Could you clarify what you mean by "auto-suggest"? Do you mean auto-complete, or something like helm or ido-mode?
    – Dan
    Dec 3, 2015 at 18:07
  • Yes, ido-mode is enabled and that's the sort of behavior I'm looking for. Sorry I didn't mention this.
    – 147pm
    Dec 3, 2015 at 19:02
  • Found emacswiki.org/emacs/InteractivelyDoThings and am looking at (ido-completing-read "What, ... is your favorite color? " mylist) section. Need it to work with my list.
    – 147pm
    Dec 3, 2015 at 19:29
  • . . . seems like I need to convert the list elements to strings to fit into ido-completing-read
    – 147pm
    Dec 3, 2015 at 19:47

2 Answers 2


With a combination of ido-completing-read and a conversion of the list items to strings, we may achieve this effect:

(setq mystrlist (mapcar (lambda (l-item) (format "%s" l-item)) mylist))


(ido-completing-read "What is your favorite thing? " mystrlist)

Running this should pop up each list item as a possible completion.


My suggestion is to use code like this:

(let ((lst '(("John" . "John Smith")
             ("James" . "James Bond"))))
  (assoc (completing-read "Test" lst) lst))

Here, lst is an alist, which is a valid collection type to pass to completing-read. If you want completing-read to use Ido, use ido-ubiquitous to set completing-read-function accordingly. But the code above automatically will adapt to whatever completing mode you have (default/helm/ido/ivy).

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