pull the relative-link-adjustment rule into a procedure

main.scm

@@ -116,6 +116,15 @@
     (a (@ (title "Permalink to this section")
           (href "#" ,slug))))))
 
+(define (adjust-relative-link tag inner)
+  (let ((linkurl (alist-ref-in '(@ href) inner)))
+    `(,tag .
+      ,(if (or (not adjust-relative)
+               (any (cute string-prefix? <> linkurl)
+                    '("#" "/" "https://" "http://" "mailto:" "https://")))
+           inner
+           (alist-update-in '(@ href) (list adjust-relative linkurl) inner)))))
+
 (define (sxml-html-rules adjust-relative)
   `(;; assign all headings an id so you can link to them
     (h1        . ,enumerate-tag)
@@ -125,15 +134,7 @@
     (h5        . ,enumerate-tag)
     ;; if adjust-relative is true, all relative links should get prefixed with
     ;; the relative-root.
-    `(a .
-      ,(lambda (t i)
-         (let ((linkurl (alist-ref-in '(@ href) i)))
-           `(,t .
-             ,(if (or (not adjust-relative)
-                      (any (cute string-prefix? <> linkurl)
-                           '("#" "/" "https://" "http://" "mailto:" "https://")))
-                  i
-                  (alist-update-in '(@ href) (list adjust-relative linkurl) i))))))
+    `(a . ,adjust-relative-link)
     ;; this copied from lowdown html-serialization-rules* because it
     ;; is for some reason not exported??
     (*COMMENT* . ,(lambda (_ str) (list #\< "!--" str "--" #\>)))