From: Okam via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: 49809@debbugs.gnu.org
Subject: bug#49809: [PATCH] Add macro 'pcase-setq'
Date: Sun, 01 Aug 2021 17:20:41 +0000 [thread overview]
Message-ID: <07ad5892-3343-4c35-00e3-9753bca5f67b@protonmail.com> (raw)
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Hello,
This patch adds a `setq`-like equivalent to `pcase-let`. This is
convenient when one wants the bindings to exist outside of a `let` form.
This macro expands into multiple `setq` calls that are combined where
possible.
;; => (1 2 3 4)
(let (a b c d)
(pcase-setq a 1
b 2
`[,c ,d] [3 4])
(list a b c d))
Please let me know what should be changed.
Thank you.
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From 824d3b56b5f4bd1aac1b933c353715155edc7698 Mon Sep 17 00:00:00 2001
From: Earl Hyatt <okamsn@protonmail.com>
Date: Sun, 1 Aug 2021 12:33:14 -0400
Subject: [PATCH] Add macro 'pcase-setq'
* doc/lispref/control.texi: Document this macro.
* lisp/emacs-lisp/pcase.el: Add this macro.
This macro is the 'setq' equivalent of 'pcase-let'.
---
doc/lispref/control.texi | 4 ++++
etc/NEWS | 4 ++++
lisp/emacs-lisp/pcase.el | 41 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 49 insertions(+)
diff --git a/doc/lispref/control.texi b/doc/lispref/control.texi
index 5026d0a4d7..a0540005d2 100644
--- a/doc/lispref/control.texi
+++ b/doc/lispref/control.texi
@@ -1312,6 +1312,10 @@ Destructuring with pcase Patterns
up being equivalent to @code{dolist} (@pxref{Iteration}).
@end defmac
+@defmac pcase-setq pattern value@dots{}
+Bind variables to values in a @code{setq} form, destructuring each
+@var{value} according to its respective @var{pattern}.
+@end defmac
@node Iteration
@section Iteration
diff --git a/etc/NEWS b/etc/NEWS
index 95a2c87d05..0f11caf512 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -553,6 +553,10 @@ The new 'cl-type' pattern compares types using 'cl-typep', which allows
comparing simple types like '(cl-type integer)', as well as forms like
'(cl-type (integer 0 10))'.
+*** New macro 'pcase-setq'
+This macro is the 'setq' equivalent of 'pcase-let', which allows for
+destructuring patterns in a 'setq' form.
+
+++
** profiler.el
The results displayed by 'profiler-report' now have the usage figures
diff --git a/lisp/emacs-lisp/pcase.el b/lisp/emacs-lisp/pcase.el
index 006517db75..f9665eba97 100644
--- a/lisp/emacs-lisp/pcase.el
+++ b/lisp/emacs-lisp/pcase.el
@@ -317,6 +317,47 @@ pcase-dolist
(pcase-let* ((,(car spec) ,tmpvar))
,@body)))))
+;;;###autoload
+(defmacro pcase-setq (&rest args)
+ "Bind values by destructuring with `pcase'.
+
+\(fn PATTERN VALUE PATTERN VALUE ...)"
+ (declare (debug (&rest [pcase-PAT form])))
+ (let ((results)
+ (pattern)
+ (value))
+ (while args
+ (setq pattern (pop args)
+ value (pop args))
+ (push (if (pcase--trivial-upat-p pattern)
+ (list 'setq pattern value)
+ (pcase-compile-patterns
+ value
+ (list (cons pattern
+ (lambda (varvals &rest _)
+ (cons 'setq
+ (mapcan (lambda (varval)
+ (let ((var (car varval))
+ (val (cadr varval)))
+ (list var val)))
+ varvals)))))))
+ results))
+
+ ;; Combine multiple calls to `setq' to a single call where we can.
+ (let ((returned-setqs)
+ (combining))
+ (dolist (i results)
+ (if (eq (car i) 'setq)
+ (push (cdr i) combining)
+ (when combining
+ (push `(setq ,@(apply #'append combining))
+ returned-setqs)
+ (setq combining nil))
+ (push i returned-setqs)))
+ (when combining
+ (push `(setq ,@(apply #'append combining))
+ returned-setqs))
+ (macroexp-progn returned-setqs))))
(defun pcase--trivial-upat-p (upat)
(and (symbolp upat) (not (memq upat pcase--dontcare-upats))))
--
2.25.1
next reply other threads:[~2021-08-01 17:20 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-01 17:20 Okam via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2021-08-04 7:14 ` bug#49809: [PATCH] Add macro 'pcase-setq' Lars Ingebrigtsen
2021-08-04 23:06 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-05 1:02 ` Michael Heerdegen
2021-08-05 13:34 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-05 15:00 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-06 1:42 ` Michael Heerdegen
2021-08-06 4:07 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-06 4:28 ` Michael Heerdegen
2021-08-06 22:33 ` Okam via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-07 2:11 ` Michael Heerdegen
2021-08-11 21:57 ` Lars Ingebrigtsen
2021-08-12 6:13 ` Michael Heerdegen
2021-08-12 12:11 ` Okam via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-12 15:06 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-13 2:55 ` Michael Heerdegen
2021-08-13 5:17 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-13 5:26 ` Michael Heerdegen
2021-08-07 15:42 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-09 0:28 ` Michael Heerdegen
2021-08-09 12:51 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-10 3:13 ` Michael Heerdegen
2021-08-12 16:13 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
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