From a5f905f8c0656c5ea8ee957a5abc2e0dc7aa0193 Mon Sep 17 00:00:00 2001
From: Arun Isaac
Date: Tue, 28 Jun 2022 10:06:12 +0530
Subject: document: Add slot-set utility.

* tissue/document.scm (slot-set): New public function.
---
 tissue/document.scm | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

(limited to 'tissue/document.scm')

diff --git a/tissue/document.scm b/tissue/document.scm
index 45de014..70a3263 100644
--- a/tissue/document.scm
+++ b/tissue/document.scm
@@ -28,7 +28,8 @@
   #:use-module (term ansi-color)
   #:use-module (xapian xapian)
   #:use-module (tissue utils)
-  #:export (object->scm
+  #:export (slot-set
+            object->scm
             scm->object
             <document>
             document-title
@@ -41,6 +42,13 @@
             file-document-path
             read-gemtext-document))
 
+(define (slot-set object slot-name value)
+  "Set SLOT-NAME in OBJECT to VALUE. This is a purely functional setter
+that operates on a copy of OBJECT. It does not mutate OBJECT."
+  (let ((clone (shallow-clone object)))
+    (slot-set! clone slot-name value)
+    clone))
+
 ;; We override the default write to print object slots and values.
 (define-method (write (object <object>) port)
   "Write OBJECT to PORT."
-- 
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