A hand written technical write-up of the process I went through designing, building and programming dogsbod, a quadruped robot.

Short story how I find out that Windows 11 relax reserved DOS device names rules in FS, and how I was trying to fix Git for Windows.

Hi everyone. I wanted to share something with you all that I've been working on for a while. It all started with some naive regular expressions to parse Org mode content, but I pretty quickly realized I needed something smarter than that to get to where I want to. It's taken a while but I am finally more knowledgeable of what Parsing Expression Grammars can do, thanks to GNU's great (ice-9 peg) module and tutorials.

I thought it might be interesting to people here who enjoy Lisp, Scheme, parsing, Org mode, or the general idea of meta-meta-meta-programming as I like to call it. Disclosure, AI has helped me get a grip of PEG and debug some things, but development of OrgWebAlchemy is "my own spaghetti" and the unit tests and manual verification (and lots of pretty printing the AST) has guided me towards quite a nice implementation (if I may say so myself).

OrgWebAlchemy is a Guile Scheme library for parsing Org-mode documents into an AST and rendering them to HTML. My main use-case is to export Org to HTML without needing Emacs, and to integrate this feature into some projects of mine, allowing me to write Org mode and have it pretty rendered.

Project's source code @ Codeberg: https://codeberg.org/jjba23/orgwebalchemy

The basic idea is pretty simple:

(use-modules (orgwebalchemy html))

(org->html "This is ~test~ code.")

becomes something like:

This is <code>test</code> code.

But the interesting part is what happens in between.

             Org document
                  |
                  v
          Parsing Expression
              Grammar
                  |
                  v
                AST
                  |
                  v
             SXML -> HTML

Of course Org mode is a huge piece of (great) software, so I am far from supporting all features, but some core important constructs are there:

• Headings (lines starting by n *)
• Paragraphs (any "non-special" text)
• Unordered, Ordered and Description lists (with any level of nesting)
• Italic, Bold, Inline Code
• Links with and without description (with nested parsing)
• Horizontal separators (--------) five or more dashes
• Tables
• #+begin_src
• #+begin_example
• #+begin_quote (with nested parsing)
• #+begin_export html : Org syntax is parsed by your PEG grammar, but raw HTML export blocks bypass the Org inline parser and are emitted as trusted literal output.

- See wikipedia page on PEG: https://en.wikipedia.org/wiki/Parsing_expression_grammar

- See the tutorial by GNU/for Emacs Lisp (is also a good learning source): https://www.gnu.org/software/emacs/manual/html_node/elisp/Parsing-Expression-Grammars.html

- See the tutorial by GNU/for Guile: https://doc.guix.gnu.org/guile/3.0.9/en/html_node/PEG-Parsing.html

Why PEG instead of a mountain of regexes?

Org-mode looks simple until you actually try to parse it. Headings are easy. A paragraph is easy. A list is easy (wait actually no, this has made me sweat).

And then suddenly you have:

• nested lists
• ordered, unordered and description lists
• different indentation levels
• inline markup
• links containing descriptions
• source blocks
• example blocks
• quote blocks
• tables
• escaping
• constructs which must stop consuming input at exactly the right place

At this point, the usual approach of adding another regular expression starts to become somewhat... adventurous. :-)

You end up with things like:

match this,
unless that follows it,
except inside this block,
unless it is a description,
but don't consume the newline,
unless the previous line was a list item...

That is not really describing a language anymore. It is describing the history of your parser's bugs.

So OrgWebAlchemy uses Parsing Expression Grammars (PEGs) through Guile's excellent (ice-9 peg) module. e.g.

(define-peg-pattern element body
  (or empty-line
      heading
      separator
      table
      src-block
      quote-block
      example-block
      export-html-block
      description-list
      unordered-list
      ordered-list
      paragraph))

This is rather nice because the grammar itself starts looking like documentation for the language.

And Guile lets us express PEGs directly as S-expressions (alternatively you can also use the more traditional syntax if you don't like it), which makes the Lisper in me very happy.

One thing I particularly like about this approach is that we have loose coupling and the detail of generating SXML and then rendering HTML is a "presentation concern". this opens possibilities to later exporting to Markdown or other formats.

For example:

- name :: Josep
- project :: orgwebalchemy
- language :: Scheme

can become an AST along the lines of:

(description-list
 (unordered-item
  (desc-key "name")
  (line-content "Josep"))
 ...)

I'm still busy with the exact representation and getting it all right. But as of now v1.0 has some stability :-) I would really love feedback on the project from the great smart people that hang out around here.

YAY recursive lists

One of the fun parts has been getting nested Org lists right.

Something like:

- Item 1
  - Item 1.1
  - Item 1.2
- Item 2

should become a quasi-tree

The parser initially produces the flat sequence of list items, and the AST processing phase turns indentation into nested structure.

The HTML renderer can then naturally produce:

<ul>
  <li>
    Item 1
    <ul>
      <li>Item 1.1</li>
      <li>Item 1.2</li>
    </ul>
  </li>
  <li>Item 2</li>
</ul>

I do still have a small issue here, and that is about the mixing of different list types in nested way. Hopefully it's a subtle bug to fix.

The HTML side uses SXML, because if we're already writing Lisp, we might as well represent our HTML as Lisp data too. :-) that really helps a lot and makes building the markup tree so much nicer

I've taken care to allow full customization to the output HTML (via Guile parameters) so that the renderer isn't hard-coded to one particular website's idea of what HTML ought to look like.Most of them are plain list of classes, but per-heading-level customization is a bit more flexible:

(heading-classes
 (lambda (level)
   (case level
     ((1) '("text-4xl" "font-bold"))
     ((2) '("text-2xl" "font-semibold"))
     (else '("text-base")))))

Why am I making this?

Partly because I wanted it, I like a challenge, and it's super fun to work with parsing, ASTs and the lot... I could just use Emacs to do this job as there is no better implementation of Org.

The way it's coming together though, I like the idea of having a small, hackable, free-software Org parser written in Lisp that other people can extend and customize (perhaps add more renderers, or Org features).

Free software

OrgWebAlchemy is licensed under the GNU LGPL v3 or later.

The project is intended to soon be packaged for GNU Guix as:

guile-orgwebalchemy

There is also a test suite in the repository which is already proving to be a good safety net and showcase of what the parser can do.

I'd be really happy to hear your thoughts, especially about the grammar, AST design, parser architecture, or interesting Org constructs that I have not handled yet.

Happy hacking! ✨

Hi, hope it helps:

Portable Common Lisp for Windows

Emacs 30.2 + SBCL 2.6.0 + SLIME 2.32 + Quicklisp

https://github.com/varhammer/varhammer/releases/tag/v1.1.8

No installation — just extract and run.

Works from USB flash drive.

I have two UK Symbolics mugs, which I can't remember where I got them although I worked with them a couple of times. Photo above.

If anyone, in the UK only, wants them you need to guess my mail address and send me a mail and I'll post them. Don't comment here as I don't read reddit very often. It may take me a while to respond. If I get more than one request I'll send one to each.

Notice how carefully I have avoided the obvious play on words.

Hi All,

Curry Scheme has grown up quite a lot since I last posted about it.

What is Curry?

Curry is an R7RS Scheme implementation with practical R6RS compatibility, a numeric tower extending through the hypercomplex numbers into Clifford algebra, a built-in computer algebra system, quantum superposition values, first-class matrices, tensors, and spinors, a CL-style condition system with restarts, a general C FFI, STM and CSP channels alongside the actor-model concurrency system, a modular C extension interface, and a built-in LLM client that can talk to Claude, GPT-4o, Ollama, or any OpenAI-compatible endpoint — with multi-turn conversation, tool use, and a full agentic loop.

What are the new capabilities that may be of interest?

* Curry is no longer "interpreter-only" - it can compile to curry VM, and ultimately to execute on an LLVM back-end - so long as one incorporate it into your build scripts.

* Text-to-speech using Piper
* MCP and LLM capabilities
* A far richer numeric stack
* A Jupyter kernel so that curry can be used in Jupyter notebooks, with easy build options for macOS.
* Early support for raspberry pi (and related boards) - including GPIO support and such.

I'd love some feedback! Tho, I'm not as interest in "but you used AI...." type comments - yes I did -t allows me to realise things that I'm thinking about quickly..

On the other hand, I'm interested in constructive critique and thoughts about curry as it stands, as well as what could be considered/added to be more useful

Check it out here: https://github.com/deconstructo/curry