From: Artur Malabarba <arturmalabarba@gmail.com>
To: Stefan Kangas <stefankangas@gmail.com>
Cc: Spencer Baugh <sbaugh@janestreet.com>, 66509@debbugs.gnu.org
Subject: bug#66509: 29.1.50; let-alist should support numeric indexing
Date: Mon, 16 Sep 2024 23:07:33 -0300 [thread overview]
Message-ID: <CAAdUY-JAD73gRQFJXHbVh30H2FLpdvLBVNsNci5o+wGqeST+tQ@mail.gmail.com> (raw)
In-Reply-To: <CADwFkmnA477c-DAMjZD5Q4xYQ4aG=No1CBLPP53+pfeSBBYqfQ@mail.gmail.com>
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Hi all,
The patch looks good.
Stefan, would you mind applying it? (It'll take a while for me to get
everything configured.)
best,
Artur
On Tue, 10 Sept 2024 at 20:22, Stefan Kangas <stefankangas@gmail.com> wrote:
> Artur, do you have any thoughts on the below patch?
>
> Spencer Baugh <sbaugh@janestreet.com> writes:
>
> > From 28e52a343f72dddd991cafd23fea910cc5f64ac5 Mon Sep 17 00:00:00 2001
> > From: Spencer Baugh <sbaugh@janestreet.com>
> > Date: Thu, 12 Oct 2023 18:01:46 -0400
> > Subject: [PATCH] Support numeric indexing in let-alist
> >
> > let-alist is very useful. But sometimes an alist contains a list in
> > the middle, which contains yet more alists. Previously, this was
> > somewhat painful to deal with, and required something like:
> >
> > (let-alist alist
> > (let-alist (nth 0 .a)
> > (let-alist (nth 3 .b)
> > .c)))
> >
> > Now, the following works:
> >
> > (let-alist alist
> > .a.0.b.3.c)
> >
> > * lisp/emacs-lisp/let-alist.el (let-alist--access-sexp): Properly
> > parse numbers.
> > (let-alist--list-to-sexp): Use nth to handle numbers.
> > (let-alist): Update docs.
> > ---
> > lisp/emacs-lisp/let-alist.el | 25 +++++++++++++++----------
> > 1 file changed, 15 insertions(+), 10 deletions(-)
> >
> > diff --git a/lisp/emacs-lisp/let-alist.el b/lisp/emacs-lisp/let-alist.el
> > index d9ad46b2af7..de7c087bf2a 100644
> > --- a/lisp/emacs-lisp/let-alist.el
> > +++ b/lisp/emacs-lisp/let-alist.el
> > @@ -36,22 +36,23 @@
> > ;; symbol inside body is let-bound to their cdrs in the alist. Dotted
> > ;; symbol is any symbol starting with a `.'. Only those present in
> > ;; the body are let-bound and this search is done at compile time.
> > +;; A number will result in a list index.
> > ;;
> > ;; For instance, the following code
> > ;;
> > ;; (let-alist alist
> > -;; (if (and .title .body)
> > +;; (if (and .title.0 .body)
> > ;; .body
> > ;; .site
> > ;; .site.contents))
> > ;;
> > ;; essentially expands to
> > ;;
> > -;; (let ((.title (cdr (assq 'title alist)))
> > +;; (let ((.title.0 (nth 0 (cdr (assq 'title alist))))
> > ;; (.body (cdr (assq 'body alist)))
> > ;; (.site (cdr (assq 'site alist)))
> > ;; (.site.contents (cdr (assq 'contents (cdr (assq 'site
> alist))))))
> > -;; (if (and .title .body)
> > +;; (if (and .title.0 .body)
> > ;; .body
> > ;; .site
> > ;; .site.contents))
> > @@ -93,14 +94,17 @@ let-alist--access-sexp
> > (if (string-match "\\`\\." name)
> > clean
> > (let-alist--list-to-sexp
> > - (mapcar #'intern (nreverse (split-string name "\\.")))
> > + (mapcar #'read (nreverse (split-string name "\\.")))
> > variable))))
> >
> > (defun let-alist--list-to-sexp (list var)
> > "Turn symbols LIST into recursive calls to `cdr' `assq' on VAR."
> > - `(cdr (assq ',(car list)
> > - ,(if (cdr list) (let-alist--list-to-sexp (cdr list) var)
> > - var))))
> > + (let ((sym (car list))
> > + (rest (if (cdr list) (let-alist--list-to-sexp (cdr list) var)
> > + var)))
> > + (cond
> > + ((numberp sym) `(nth ,sym ,rest))
> > + (t `(cdr (assq ',sym ,rest))))))
> >
> > (defun let-alist--remove-dot (symbol)
> > "Return SYMBOL, sans an initial dot."
> > @@ -116,22 +120,23 @@ let-alist
> > "Let-bind dotted symbols to their cdrs in ALIST and execute BODY.
> > Dotted symbol is any symbol starting with a `.'. Only those present
> > in BODY are let-bound and this search is done at compile time.
> > +A number will result in a list index.
> >
> > For instance, the following code
> >
> > (let-alist alist
> > - (if (and .title .body)
> > + (if (and .title.0 .body)
> > .body
> > .site
> > .site.contents))
> >
> > essentially expands to
> >
> > - (let ((.title (cdr (assq \\='title alist)))
> > + (let ((.title (nth 0 (cdr (assq \\='title alist))))
> > (.body (cdr (assq \\='body alist)))
> > (.site (cdr (assq \\='site alist)))
> > (.site.contents (cdr (assq \\='contents (cdr (assq \\='site
> alist))))))
> > - (if (and .title .body)
> > + (if (and .title.0 .body)
> > .body
> > .site
> > .site.contents))
>
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next prev parent reply other threads:[~2024-09-17 2:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-12 22:03 bug#66509: 29.1.50; let-alist should support numeric indexing Spencer Baugh
2023-10-12 22:04 ` Spencer Baugh
2024-09-10 23:22 ` Stefan Kangas
2024-09-17 2:07 ` Artur Malabarba [this message]
2024-09-19 1:56 ` Stefan Kangas
2024-09-19 5:56 ` Eli Zaretskii
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