Hello, I decided to write a little bit about one of my projects and I thought it might be of interest to people in here. It’s still in early stage but the consept works and I’m building other projects on top of it. Of which I will try to write about later too.
Feedback of both the library and blog post is appreciated. 
And here is the new one, much more hands on and propably illuminates things much better. I hope. 
Retropikzel’s website - Blog - 2024-06-21 - r7rs-pffi libcurl example
Thanks, this is interesting. Makes me think about trying to use libcurl from an Emacs module, which has been discussed for years. It’s a shame that you can’t pass a callback through the FFI; that seems to be a serious drawback for this example.
Minor feedback: sometimes it’s hard to tell whether a code block is described by the paragraph before or after it. You might try to visually associate a code block with the descriptive text, or at least do something like write the descriptive paragraph before the code and end the paragraph with a colon, which would indicate that what it describes is to follow.
Also, there seem to be a couple of paragraphs and code blocks that are duplicated before the full code block.
Thanks for the feedback! I updated the post for more clarity. Some comments were before code blocks. Some after. Due to me trying to switch them around after writing the whole thing. I switched all to comment first then code and added some margin after the code block.
I chose my first example little poorly. I did not know that libcurl uses callbacks before I started writing. I’ve been using this mostly with SDL2 which does not use them at all to my knowledge. I did not make example with SDL2 (yet) as I thought libcurl would make shorter and easier example and be usefull to more people.
Now that I’ve encountered a place where callbacks are needed I have to at some point investigate if all the implementations I want to support, support callbacks. Having libcurl working would be tremendously usefull.
Just update that callbacks are possible and I will be implementing support for them.
Support for callbacks in Sagittarius is already done.
I was interested in the topic, but the links seem to be dead for me.
Sorry, I moved my website and forgot to update here. Here are updated links.
Linkin to my blog: Retropikzel's website - Blog
Project: r7rs-pffi: Portable Foreign Function Interface for R7RS Scheme
The interface has changed, but just a bit, auto-load takes only two required arguments and there is now way to make structs. I tried to update the blog posts and example code on all the places needed.
If anyone else is interested, support for some implementations is as of writing considered to be in (early) beta:
If you run into problems/have questions please let me know either here or on the mailing lists/tickets of the project.