From 6692d8454a89e542d85d2b6a93adfd373aeec39c Mon Sep 17 00:00:00 2001 From: nee Date: Wed, 25 Oct 2017 20:44:54 +0200 Subject: guix: records: Add match-record. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * guix/records.scm: New syntax-rule. Signed-off-by: Ludovic Courtès --- guix/records.scm | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) (limited to 'guix/records.scm') diff --git a/guix/records.scm b/guix/records.scm index 7de5fccef6..1f00e16603 100644 --- a/guix/records.scm +++ b/guix/records.scm @@ -26,7 +26,8 @@ #:export (define-record-type* alist->record object->fields - recutils->alist)) + recutils->alist + match-record)) ;;; Commentary: ;;; @@ -375,4 +376,19 @@ pairs. Stop upon an empty line (after consuming it) or EOF." (else (error "unmatched line" line)))))))) +(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 ...)) + (throw 'wrong-type-arg record))) + ((_ record type () body ...) + (begin body ...)))) + ;;; records.scm ends here -- cgit v1.2.3