cffi VS dhall

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.

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If you mean installing Dhall's dependencies (https://github.com/dhall-lang/dhall-haskell/blob/master/dhal...), those aren't too crazy, but they're definitely not all "beginner level". Template Haskell in particular is quite heavyweight.

Ok, lets be specific. Lets write a comment to explain this function:

https://github.com/dhall-lang/dhall-haskell/blob/master/dhal...

I haven't tried it but apparently you can compile to Nix from Dhall:

> You can use this compiler to program Nix using the Dhall language. This package targets people who wish Nix had a type system.

https://github.com/dhall-lang/dhall-haskell/tree/master/dhal...

If the problem is the syntax and people wants some other format that compiles to nix, there's dhall

https://dhall-lang.org/

https://github.com/dhall-lang/dhall-haskell/tree/master/dhal...

https://www.haskellforall.com/2017/01/typed-nix-programming-...

Dhall is a generic config language with some programming capabilities (but not turing complete) that can compile to json, yaml, and other formats, like in this instance nix.

For my GSoC project, I built from scratch the dhall-csv package on the Dhall Haskell implementation Github Repository. Said package provides two executables, dhall-to-csv (which converts Dhall files into CSV files) and csv-to-dhall (which converts CSV files into Dhall files). It also provides Haskell libraries with the functions that translate bidirectionally between Dhall and CSV.

> If you add constraints (like not being able to feed the program to itself as is done in the halting problem and not allowing unbounded loops) then it is possible to determine if a program will terminate or not.

Dhall is a good example - https://github.com/dhall-lang/dhall-haskell .

See also https://dhall-lang.org/

That just seems like an even greater nightmare to me. Soon you would have to learn to read and understand a custom program in a Turing-complete language for each and every installation.

The proper solution is a DSL, just a better DSl. Or perhaps a DSL embedded in something like dhall <https://dhall-lang.org/>, but definitely not a general-purpose programming language.

Dhall