GNU bug report logs - #60225
[PATCH] records: match-record supports specifying a different variable name.

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

From: Attila Lendvai <attila <at> lendvai.name>
To: guix-patches <at> gnu.org
Cc: Attila Lendvai <attila <at> lendvai.name>
Subject: [PATCH] records: match-record supports specifying a different
 variable name.
Date: Tue, 20 Dec 2022 14:40:19 -0300

An example:

(match-record obj <my-type>
  (field1 (field2 custom-var-name) field3)
  ...)
---
 guix/records.scm | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/guix/records.scm b/guix/records.scm
index 13463647c8..0b2487a156 100644
--- a/guix/records.scm
+++ b/guix/records.scm
@@ -592,13 +592,16 @@ (define-syntax lookup-field
 (define-syntax match-record-inner
   (lambda (s)
     (syntax-case s ()
-      ((_ record type (field rest ...) body ...)
-       #`(let-syntax ((field-offset (syntax-rules ()
+      ((_ record type ((field-name variable-name) rest ...) body ...)
+       #'(let-syntax ((field-offset (syntax-rules ()
 			              ((_ f)
-                                       (lookup-field field 0 f)))))
+                                       (lookup-field field-name 0 f)))))
            (let* ((offset (type map-fields field-offset))
-                  (field  (struct-ref record offset)))
+                  (variable-name (struct-ref record offset)))
              (match-record-inner record type (rest ...) body ...))))
+      ((_ record type (field rest ...) body ...)
+       ;; Redirect to the canonical form above.
+       #'(match-record-inner record type ((field field) rest ...) body ...))
       ((_ record type () body ...)
        #'(begin body ...)))))
 
-- 
2.35.1

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