Safsaf – A Web Framework for Guile(codeberg.org)

Background

Over the past week or two I've been working on a new web framework for
Guile. This is based on the knowledge I've accumulated over the past 7
years working on things like the Guix Data
Service, Guix Build
Coordinator and Nar
Herder, but also based on their
code, as I've used Claude Code running Claude Opus 4.6 to build this
(a large language model).

I've been hesitant to try coding with LLMs so far, I still think
there's plenty of reasons to be, and others have done much more
thinking about LLMs and the ethical and legal implications of using
them to write software.

This blog post definitely isn't an argument for using these tools, but
my "excuse" if you call it that, is that I wanted a Guile web
framework to both use for existing and new projects, and this was an
approach to get there faster and with the limited amount of motivation
I have at the moment.

Introducing Safsaf

Safsaf, or Guile Safsaf
if you prefer, is a web framework for Guile, built around using
Guile Fibers and the Guile
Knots web
server.

It's only ~1800 lines of code, and the largest part is the router,
deciding which handler should respond to requests. The Guix Data
Service handled routing using match on the method and path
components, and this works pretty well, but for a long while I've
wanted a more declarative approach to routing. One where the code
could introspect the routes and generate links or even API
specifications.

Another important property of having routes as data is that it allows
applying handler wrappers to the routes and the handlers that they
reference. This is the model that Safsaf uses for middleware or
functionality that you want to apply across some or all of the web
service. Safsaf comes with a number of useful handler wrappers and
functionality like logging and exception handling is implemented as
handler wrappers.

I think it's also important what's not included. In comparison to
GNU Artanis (which I did try using for the
Guix Data Service many years ago), there's no inbuilt support for
talking to databases, database migrations, a Model View Controller
design or file based templates, and for all these things, I don't
currently see a good reason to include support for them.

I would like to look at what can be included for internationalization
support, as I think that's important. I'd also like to look at what's
required for Server Sent Events (SSE) and WebSocket support,
particularly as the Build Farm Front-end (BFFE) uses Server Sent
Events.

The Safsaf Git repository includes a couple of example apps which you
can run, a
paste-bin
and a blog
site.

There's inevitably some issues with the code, and there's probably
some issues with the design as well, but my hope is that this is a
good starting point.

If you have any comments or questions, please reach out to me via
email at mail@cbaines.net, raise an issue
on Forgejo, or contact me
on the Fediverse.

Source: https://codeberg.org/guix/data-service