dhall-lang VS dhall

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/

```

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