added RSS and pages

build.py

@@ -1,16 +1,20 @@
 #!/usr/bin/env python3
-"""Build the blog: every topics/**/*.md becomes a section in one index.html.
+"""Build the blog: every topics/**/*.md becomes its own page at <slug>/,
+index.html lists them all with a short teaser, and feed.xml is an RSS feed
+with every post in full.
 
 Each post may start with a small header:
 
     ---
     title: My first post
     date: 2026-10-03
+    description: One or two sentences for the teaser and search results.
     ---
 
-Without it, the title comes from the first "# Heading" (or the file name)
+Without it, the title comes from the first "# Heading" (or the file name),
-and the date from a YYYY-MM-DD file-name prefix, if any. A post in a
+the date from a YYYY-MM-DD file-name prefix, if any, and the description
-subfolder (topics/python/foo.md) is tagged with that folder's name.
+from the first paragraph. A post in a subfolder (topics/python/foo.md) is
+tagged with that folder's name.
 
 Usage: python3 build.py [source_dir] [output_dir]
 """
@@ -18,7 +22,8 @@ import html
 import re
 import shutil
 import sys
-from datetime import date
+from datetime import date, datetime, time, timezone
+from email.utils import format_datetime
 from pathlib import Path
 
 import markdown
@@ -26,6 +31,9 @@ import markdown
 SRC = Path(sys.argv[1] if len(sys.argv) > 1 else ".").resolve()
 OUT = Path(sys.argv[2] if len(sys.argv) > 2 else "public").resolve()
 TOPICS = SRC / "topics"
+SITE_URL = "https://pascal-maas.nl"
+SITE_NAME = "Pascal Maas"
+SITE_DESCRIPTION = "A blog about bioinformatics in metabolomics"
 
 
 def slugify(text):
@@ -59,54 +67,173 @@ def parse(path):
         sys.exit(f"{path.relative_to(SRC)}: date '{raw_date}' is not YYYY-MM-DD")
 
     rel = path.relative_to(TOPICS)
-    return {
+    body = markdown.markdown(
-        "title": title,
-        "date": when,
-        "topic": rel.parts[0] if len(rel.parts) > 1 else meta.get("topic"),
-        "slug": slugify(meta.get("slug") or re.sub(r"^\d{4}-\d{2}-\d{2}-", "", path.stem)),
-        "body": markdown.markdown(
         text,
         extensions=[
             "fenced_code", "tables", "footnotes", "codehilite", "abbr",
         ],
         extension_configs={"codehilite": {"guess_lang": False}},
-        ),
+    )
+    return {
+        "title": title,
+        "date": when,
+        "topic": rel.parts[0] if len(rel.parts) > 1 else meta.get("topic"),
+        "slug": slugify(meta.get("slug") or re.sub(r"^\d{4}-\d{2}-\d{2}-", "", path.stem)),
+        "summary": meta.get("description") or first_paragraph(body),
+        "body": body,
     }
 
 
-def main():
+def first_paragraph(body):
-    posts = [parse(p) for p in sorted(TOPICS.rglob("*.md"))]
+    """Plain text of the first paragraph, without footnote markers."""
-    # Newest first; undated posts go last.
+    match = re.search(r"<p>(.*?)</p>", body, re.S)
-    posts.sort(key=lambda p: (p["date"] is not None, p["date"] or date.min), reverse=True)
+    if not match:
+        return ""
+    text = re.sub(r"<sup.*?</sup>", "", match.group(1), flags=re.S)
+    text = html.unescape(re.sub(r"<[^>]+>", "", text))
+    return " ".join(text.split())
 
+
+def load_posts():
+    """All posts, newest first (undated last), with unique slugs."""
+    posts = [parse(p) for p in sorted(TOPICS.rglob("*.md"))]
+    posts.sort(
+        key=lambda p: (p["date"] is not None, p["date"] or date.min),
+        reverse=True,
+    )
     seen = {}
-    for p in posts:  # keep anchors unique
+    for p in posts:  # keep page folders unique
         n = seen.get(p["slug"], 0)
         seen[p["slug"]] = n + 1
         if n:
             p["slug"] += f"-{n + 1}"
+    return posts
 
-    toc, sections = [], []
+
-    for p in posts:
+def time_tag(post):
-        title = html.escape(p["title"])
+    if not post["date"]:
-        when = f'<time datetime="{p["date"].isoformat()}">{p["date"]:%d %B %Y}</time>' if p["date"] else ""
+        return ""
-        tag = f'<span class="tag">{html.escape(p["topic"])}</span>' if p["topic"] else ""
+    return (
-        toc.append(f'<li><a href="#{p["slug"]}">{title}</a>{when}</li>')
+        f'<time datetime="{post["date"].isoformat()}">'
-        sections.append(
+        f'{post["date"]:%d %B %Y}</time>'
-            f'<article id="{p["slug"]}">\n'
-            f'<header><h2><a href="#{p["slug"]}">{title}</a></h2><p class="meta">{when}{tag}</p></header>\n'
-            f'{p["body"]}\n</article>'
     )
 
-    page = (SRC / "template.html").read_text(encoding="utf-8")
-    page = page.replace("{{toc}}", "\n".join(toc) or "<li>No posts yet.</li>")
-    page = page.replace("{{posts}}", "\n\n".join(sections))
-    page = page.replace("{{year}}", str(date.today().year))
 
+def meta_line(post):
+    tag = ""
+    if post["topic"]:
+        tag = f'<span class="tag">{html.escape(post["topic"])}</span>'
+    return f'<p class="meta">{time_tag(post)}{tag}</p>'
+
+
+def render_toc(posts, current, root):
+    """The side list; the post being shown (if any) is marked current."""
+    items = []
+    for post in posts:
+        css = ' class="current"' if post is current else ""
+        items.append(
+            f'<li><a href="{root}{post["slug"]}/"{css}>'
+            f'{html.escape(post["title"])}</a>{time_tag(post)}</li>'
+        )
+    return "\n".join(items) or "<li>No posts yet.</li>"
+
+
+def index_content(posts):
+    teasers = []
+    for post in posts:
+        link = f'./{post["slug"]}/'
+        teasers.append(
+            f'<article>\n<header><h2><a href="{link}">'
+            f'{html.escape(post["title"])}</a></h2>{meta_line(post)}'
+            f'</header>\n<p>{html.escape(post["summary"])}</p>\n'
+            f'<p><a href="{link}">Read more</a></p>\n</article>'
+        )
+    return "\n\n".join(teasers)
+
+
+def rebase_static(body, prefix):
+    """Put prefix in front of the static/ paths in a post body."""
+    return re.sub(r'(src|href)="static/', rf'\1="{prefix}static/', body)
+
+
+def post_content(post):
+    # Post pages sit one folder deeper, so static/ paths need ../ in front.
+    body = rebase_static(post["body"], "../")
+    return (
+        f'<article>\n<header><h2>{html.escape(post["title"])}</h2>'
+        f'{meta_line(post)}</header>\n{body}\n</article>'
+    )
+
+
+def write_page(folder, template, posts, current, title, description, content):
+    """Fill the template for one page and write it as folder/index.html."""
+    root = "./" if current is None else "../"
+    fields = {
+        "title": html.escape(title),
+        "description": html.escape(description),
+        "root": root,
+        "toc": render_toc(posts, current, root),
+        "content": content,
+        "year": str(date.today().year),
+    }
+    for key, value in fields.items():
+        template = template.replace("{{" + key + "}}", value)
+    folder.mkdir(parents=True, exist_ok=True)
+    (folder / "index.html").write_text(template, encoding="utf-8")
+
+
+def feed_item(post):
+    link = f'{SITE_URL}/{post["slug"]}/'
+    # Feed readers show posts away from the site, so paths must be full.
+    body = rebase_static(post["body"], f"{SITE_URL}/")
+    lines = [
+        "<item>",
+        f'<title>{html.escape(post["title"])}</title>',
+        f"<link>{link}</link>",
+        f'<guid isPermaLink="true">{link}</guid>',
+    ]
+    if post["date"]:
+        moment = datetime.combine(post["date"], time(), timezone.utc)
+        lines.append(f"<pubDate>{format_datetime(moment)}</pubDate>")
+    lines.append(f"<description>{html.escape(body)}</description>")
+    lines.append("</item>")
+    return "\n".join(lines)
+
+
+def write_feed(posts):
+    """feed.xml: an RSS feed with every post in full, newest first."""
+    items = "\n".join(feed_item(post) for post in posts)
+    feed = (
+        '<?xml version="1.0" encoding="utf-8"?>\n'
+        '<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">\n'
+        "<channel>\n"
+        f"<title>{html.escape(SITE_NAME)}</title>\n"
+        f"<link>{SITE_URL}/</link>\n"
+        f"<description>{html.escape(SITE_DESCRIPTION)}</description>\n"
+        "<language>en</language>\n"
+        f'<atom:link href="{SITE_URL}/feed.xml" rel="self" '
+        'type="application/rss+xml"/>\n'
+        f"{items}\n</channel>\n</rss>\n"
+    )
+    (OUT / "feed.xml").write_text(feed, encoding="utf-8")
+
+
+def main():
+    posts = load_posts()
+    template = (SRC / "template.html").read_text(encoding="utf-8")
     if OUT.exists():
         shutil.rmtree(OUT)
-    OUT.mkdir(parents=True)
+    write_page(
-    (OUT / "index.html").write_text(page, encoding="utf-8")
+        OUT, template, posts, None, f"{SITE_NAME} · Blog", SITE_DESCRIPTION,
+        index_content(posts),
+    )
+    for post in posts:
+        write_page(
+            OUT / post["slug"], template, posts, post,
+            f'{post["title"]} · {SITE_NAME}', post["summary"],
+            post_content(post),
+        )
+    write_feed(posts)
     if (SRC / "static").is_dir():  # images etc.: topics can link to static/foo.png
         shutil.copytree(SRC / "static", OUT / "static")
     print(f"Built {len(posts)} post(s) into {OUT}")

template.html

@@ -3,7 +3,12 @@
 <head>
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
-<title>Pascal Maas · Blog</title>
+<title>{{title}}</title>
+<meta name="description" content="{{description}}">
+<meta property="og:title" content="{{title}}">
+<meta property="og:description" content="{{description}}">
+<link rel="alternate" type="application/rss+xml" title="Pascal Maas"
+      href="{{root}}feed.xml">
 <script>
   // Runs before the page is drawn, so a saved dark choice doesn't flash.
   try {
@@ -16,19 +21,19 @@
   /* Served from static/; Georgia shows until these have loaded. */
   @font-face {
     font-family: "Poltawski Nowy"; font-weight: 400; font-style: normal;
-    src: url("static/PoltawskiNowy-Regular.ttf"); font-display: swap;
+    src: url("{{root}}static/PoltawskiNowy-Regular.ttf"); font-display: swap;
   }
   @font-face {
     font-family: "Poltawski Nowy"; font-weight: 400; font-style: italic;
-    src: url("static/PoltawskiNowy-Italic.ttf"); font-display: swap;
+    src: url("{{root}}static/PoltawskiNowy-Italic.ttf"); font-display: swap;
   }
   @font-face {
     font-family: "Poltawski Nowy"; font-weight: 700; font-style: normal;
-    src: url("static/PoltawskiNowy-Bold.ttf"); font-display: swap;
+    src: url("{{root}}static/PoltawskiNowy-Bold.ttf"); font-display: swap;
   }
   @font-face {
     font-family: "Poltawski Nowy"; font-weight: 700; font-style: italic;
-    src: url("static/PoltawskiNowy-BoldItalic.ttf"); font-display: swap;
+    src: url("{{root}}static/PoltawskiNowy-BoldItalic.ttf"); font-display: swap;
   }
   :root {
     --latte: #f4f2ee; --espresso: #231c15;
@@ -59,6 +64,7 @@
   .site-header h1 {
     margin: 0; font-size: 1.6rem; line-height: 1.2; letter-spacing: -0.01em;
   }
+  .site-header h1 a { color: inherit; text-decoration: none; }
   .site-header p { display: none; margin: 0; color: var(--muted); }
   .site-header {
     display: flex; justify-content: space-between;
@@ -167,7 +173,7 @@
 <div class="wrap">
   <header class="site-header">
     <div class="site-title">
-      <h1>Pascal Maas</h1>
+      <h1><a href="{{root}}">Pascal Maas</a></h1>
       <p>A blog about bioinformatics in metabolomics</p>
     </div>
     <div class="header-actions">
@@ -188,11 +194,11 @@
     </nav>
 
     <main>
-{{posts}}
+{{content}}
     </main>
   </div>
 
-  <footer>© {{year}} Pascal Maas</footer>
+  <footer>© {{year}} Pascal Maas · <a href="{{root}}feed.xml">RSS</a></footer>
 </div>
 <script>
   const root = document.documentElement;
@@ -219,9 +225,7 @@
     } catch (error) {}
   });
 
-  const header = document.querySelector(".site-header");
+  const articles = document.querySelectorAll("main article");
-  const articles = Array.from(document.querySelectorAll("main article"));
-  const links = document.querySelectorAll("nav a");
 
   // First use of each term per post keeps its definition, moved out of
   // "title" so the browser's plain tooltip doesn't show beside the bubble.
@@ -238,30 +242,6 @@
       term.tabIndex = 0;
     }
   }
-
-  // The current post is the last one whose top has passed a line 3rem
-  // (48px) below the header; at the very bottom, it is always the last post.
-  function markCurrentPost() {
-    if (articles.length === 0) {
-      return;
-    }
-    const line = header.getBoundingClientRect().bottom + 48;
-    const viewBottom = window.innerHeight + window.scrollY;
-    const atBottom = viewBottom >= root.scrollHeight - 2;
-    let current = articles[0];
-    for (const article of articles) {
-      if (atBottom || article.getBoundingClientRect().top <= line) {
-        current = article;
-      }
-    }
-    for (const link of links) {
-      link.classList.toggle("current", link.hash === "#" + current.id);
-    }
-  }
-
-  markCurrentPost();
-  window.addEventListener("scroll", markCurrentPost, { passive: true });
-  window.addEventListener("resize", markCurrentPost);
 </script>
 </body>
 </html>

topics/starting-a-blog.md

@@ -1,5 +1,6 @@
 ---
 title: Starting a blog
+description: Hi there! This is my first post in hopefully many. I'm Pascal and work as a bioinformatician in the field of metabolomics. I studied bioinformatics, getting my master degree in 2020 at the University of Amsterdam and since then I work at the Metabolomics Analytical Centre, which is part of the University of Leiden. Here I develop software to support the data analysis of large volumes of samples. This however, remains a challenge for reasons that hopefully become clear through posts on this blog. Ofcourse, I will also attempt to provide solutions for practical challenges I've encounted.
 date: 2026-10-04
 ---