(address . guix-patches@gnu.org)(name . Attila Lendvai)(address . attila@lendvai.name)
* guix/records.scm (match-record/fields): New macro.
(match-record): Only check the object type once in the expansion.
---
guix/records.scm | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
Toggle diff (37 lines)
diff --git a/guix/records.scm b/guix/records.scm
index ed94c83dac..e311086d73 100644
--- a/guix/records.scm
+++ b/guix/records.scm
@@ -535,17 +535,25 @@ (define (recutils->alist port)
(else
(error "unmatched line" line))))))))
+(define-syntax match-record/fields
+ (syntax-rules ()
+ ((_ record type (field fields ...) body ...)
+ (let ((field ((record-accessor type 'field) record)))
+ ;; TODO compute indices and report wrong-field-name errors at
+ ;; expansion time
+ ;; TODO support thunked and delayed fields
+ (match-record/fields record type (fields ...) body ...)))
+ ((_ record type () body ...)
+ (begin body ...))))
+
(define-syntax match-record
(syntax-rules ()
"Bind each FIELD of a RECORD of the given TYPE to it's FIELD name.
The current implementation does not support thunked and delayed fields."
((_ record type (field fields ...) body ...)
(if (eq? (struct-vtable record) type)
- ;; TODO compute indices and report wrong-field-name errors at
- ;; expansion time
- ;; TODO support thunked and delayed fields
- (let ((field ((record-accessor type 'field) record)))
- (match-record record type (fields ...) body ...))
+ ;; So that we only test the type once.
+ (match-record/fields record type (field fields ...) body ...)
(throw 'wrong-type-arg record)))
((_ record type () body ...)
(begin body ...))))
--
2.34.0