cffi VS dhall-lang

When you want to do anything that breaks the nice bubble of your Lisp image, you might want to know a bit about your operating system's programming interface. This will come in handy if you ever need to wrap a library with CFFI. There are some things that are pretty inconvenient as a rule (like dealing with any protocol that uses network byte order), but if you stay within the bubble of your Lisp image, you won't really notice them.

I'm just posting the work that I have done over the last year or so on CL-Objc. I'm still blocked from better support (e.g., passing structs by value for frameworks like UIKit). I just wanted to post what I have done online for others interested in the work or motivated to collaborate on this.

Good morning ladies and gentlemen, I have been waiting on some feedback for PR in CFFI. This feature is blocking me from reviving CL-OBJC. Any help will be appreciated. Thank you in advance.

Is that actually https://github.com/cffi/cffi/commit/33970351e71bb5f12ba56fc40270089e948ae112 ? I.e. after loading cl+ssl. (Although Hunchentoot does not interrupt threads)

Maybe access the pins using CFFI, https://github.com/cffi/cffi package and one the libraries mentioned here? https://www.bigmessowires.com/2018/05/26/raspberry-pi-gpio-programming-in-c/

FTR, on my system QL fetches CFFI 0.23.0 and the fix/error I'm talking about is https://github.com/cffi/cffi/blob/master/src/libraries.lisp#L106 and seems to have been added iin this PR https://github.com/cffi/cffi/pull/173/commits/263b38f4f2600dbacde8f2b313620c35a563c6df so the fix should be in CFFI 0.24.0 released 24 March 2021.

FTR: this is the PR https://github.com/cffi/cffi/pull/173/commits/263b38f4f2600dbacde8f2b313620c35a563c6df

C: Alternatively (more difficult) you could try to wrap the underlying C layers of either of those mentioned under Python with CFFI. The C-based game engine, Raylib, is also wrappable this way. I finished a super cool walking simulator in CL with that, but it is more tedious than the others since raylib is really barebones.

I feel inspired to start Lisp after being disappointed with the "open" source scene of 2021. I'd rather pay LispWorks a yearly fee and be left alone than dealing with unbalanced people in the Python space. The free Lisp implementations also look somewhat isolated from the ideological wars.

However, a C interface is required. Is this one the recommended solution? Is it really portable?

https://common-lisp.net/project/cffi/

What is the speed compared to a Python C extension? Are implementation-specific C interfaces faster (I guess they are)?

Sorry for so many questions, but these can usually only be answered by people who have actually used the interface.

Fail to see how this is any different than Dhall (https://dhall-lang.org/) other than it produces plists too.

Kubernetes config is a decent example. I had ChatGPT generate a representative silly example -- the content doesn't matter so much as the structure:

https://gist.github.com/cstrahan/528b00cd5c3a22e3d8f057bb1a7...

Now consider 100s (if not 1000s) of such files.

I haven't given Pkl an in depth look yet, but I can say that the Industry Standard™ of "simple YAML" + string substitution (with delicate, error prone indentation -- since YAML is indentation sensitive) is easily beat by any of:

- https://jsonnet.org/

- https://nickel-lang.org/

- https://nixos.org/manual/nix/stable/language/index.html

- https://dhall-lang.org/

- (insert many more here, probably including Pkl)

There are underpowered languages / tools, that can only solve a problem for which they are intended poorly. But not all limited tools are like that.

Say, eBPF is prominently not Turing-complete, which allows to guarantee that a eBPF program terminates, and even how soon. Still eBPF is hugely useful in its area.

Or, say, regular expressions are limited to regular languages; in particular, they famously [1] cannot process recursive structures, like trees. Still tools like grep / ag / rg are mightily useful.

Yes, I agree that YAML is underpowered for proper k8s configuration! But it's also too powerful for its own good in other aspects [2]. I wish Google used Dhall [3] or their own purely functional config language (FCL? I already forgot the name) instead of YAML; sadly, they did not.

[1]: https://stackoverflow.com/a/1732454/223424

[2]: https://ruudvanasseldonk.com/2023/01/11/the-yaml-document-fr...

[3]: https://dhall-lang.org/

Dhall: Dhall is a programmable configuration language that combines features like JSON, functions, types, and import capabilities. Its style leans towards functional programming, so if you're familiar with functional-style languages such as Haskell, you might find Dhall to be quite intuitive.

I've been thinking along these lines but more 'strongly validated' than statically typed in the sense that you'd be better off being able to load the entire config and then produce a list of problems (and should be able to offer good editor support if done correctly).

Though https://dhall-lang.org/ demonstrates that you can statically type quite a lot of configuration to great advantage, which appears to be programmatically embeddable in multiple languages per https://docs.dhall-lang.org/howtos/How-to-integrate-Dhall.ht...

> Where practical is in the sense of an engineer (or in their terms, a CS practitioner),

Configuration processing. E.g. I'd like my yamls to be decidable, though I'd settle for guaranteed to halt[1].

[1] https://dhall-lang.org/

Maybe you'd like jsonnet: https://jsonnet.org/

I find it particularly useful for configurations that often have repeated boilerplate, like ansible playbooks or deploying a bunch of "similar-but" services to kubernetes (with https://tanka.dev).

Dhall is also quite interesting, with some tradeoffs: https://dhall-lang.org/

A few years ago I did a small comparison by re-implementing one of my simpler ansible playbooks: https://github.com/retzkek/ansible-dhall-jsonnet

And to checkout Dhall: https://dhall-lang.org/