header id-ification improvement and other cleanup

- fixed comment rendering
- simplified pre-post-order rule for unspecified values
- limited length of header id to 40 characters + tag name

README.md

@@ -65,6 +65,7 @@ TODO
 - **feature**: display binary files as output from binary-file analysis tools like hexdump, xxd, dumpelf, elfls, readelf, etc.?
 - **feature**: syntax highlighting?
 - **feature**: markdown-render git log text
+- **feature**: other mechanisms for header id application like uniqueness checking, sequential numbering
 
 ## license: agpl-3.0+
 

main.scm

@@ -68,6 +68,10 @@
            (map (constantly "../"))
            (apply string-append))))
 
+;; like (substring) but doesn't break if start and end are too big/small
+(define (substring* s start end)
+  (substring s (max start 0) (min end (string-length s))))
+
 ;; main code ---------------------------------
 
 (define mycss
@@ -141,19 +145,25 @@
         (hr)
         (footer (p "Generated by " (a (@ href "https://git.m455.casa/repo2html/") "repo2html")))))))
 
-(define (slugify tag inner)
-  (-> inner
+(define (slugify _ inner)
+  (->
+   inner
    (pre-post-order*
-       `(
-         (*text* . ,(lambda (trig str)
-                      (-> str
+    `((*text* .
+       ,(lambda (_ str)
+          (->
+           str
+           (string-downcase)
            (string-translate "/,:;\"[]{}()=+")
-                          (string-translate "ABCDEFGHIJKLMNOPQRSTUVWXYZ _." "abcdefghijklmnopqrstuvwxyz---")
-                          )))
-         ,@alist-conv-rules*))))
+           (string-translate " _." "---"))))
+      ,@alist-conv-rules*))
+   (flatten)
+   ((flip map) ->string)
+   (string-intersperse "")
+   (substring* 0 40)))
 
 (define (enumerate-tag tag inner)
-  `(,tag (@ (id ,(slugify tag inner))) ,inner))
+  `(,tag (@ (id ,tag "-" ,(slugify tag inner))) ,inner))
 
 (define (in-git-directory?)
   (not (eof-object? (call-with-input-pipe "git rev-parse --git-dir" read-line))))
@@ -267,13 +277,11 @@
               (h3        . ,enumerate-tag)
               (h4        . ,enumerate-tag)
               (h5        . ,enumerate-tag)
-             ;; i'd expect this to be built-in, dunno why its needed
-             (*COMMENT* . ,(lambda (tag str) `("<!--" ,str "-->")))
+              ;; this copied from lowdown html-serialization-rules* because it
+              ;; is for some reason not exported??
+              (*COMMENT* . ,(lambda (_ str) (list #\< "!--" str "--" #\>)))
               ;; ignore #<unspecified> in tree
-             (*text* . ,(lambda (trigger str)
-                          (if (equal? str (unspecified-value))
-                              ""
-                              ((alist-ref '*text* alist-conv-rules*) trigger str))))
+              (*text*    . ,(lambda (_ str) (if (unspecified? str) "" str)))
               ,@alist-conv-rules*))))))
 
     (create-directory html-repo-path #t)