GNU bug report logs - #49407
Request: Specify default values in `map-let` in Map.el

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Package: emacs;

Reported by: Okam <okamsn <at> protonmail.com>

Date: Sun, 4 Jul 2021 23:10:01 UTC

Severity: wishlist

Fixed in version 30.1

Done: "Basil L. Contovounesios" <contovob <at> tcd.ie>

Bug is archived. No further changes may be made.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Okam <okamsn <at> protonmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Request: Specify default values in `map-let` in Map.el
Date: Sun, 04 Jul 2021 23:08:55 +0000

Hello,

`map-let` allows one to conveniently bind variables using `map-elt`, but
does not provide a way specify a default value if a key is missing.

With `map-elt`, one can use the optional third argument to specify this
value.  It would be good to have this in `map-let` as well.

For example, maybe it could look something like

     ;; As just a third value in the list:
     (let ((map '(:a 1 :b 2)))
       (map-let ((:a a)
                 (:b b)
                 (:c c 3))
           map
         (+ a b c)))

or

     ;; More like Common Lisp arg-list for `&key'.
     (let ((map '(:a 1 :b 2)))
       (map-let ((:a a)
                 (:b b)
                 (:c (c 3)))
           map
         (+ a b c)))

Please consider adding this feature.

Thank you.
This bug report was last modified 2 years and 2 days ago.

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