Pkl, a Programming Language for Configuration • Hacker News Board

Re: Pkl, a Programming Language for Configuration

#41

Post by iamflimflam1 » Sat, Feb 03, 2024, 11:56 AM UTC

msoad wrote: post #32

JSONSchema covers a lot of various schema needs and YAML is something a lot of developers are comfortable with. I know both of those technologies are not popular here in HN but YAML type-checked and editor-autocomplete-enabled using JSONSchema is a solid choice for configurations in my opinion.

Every time I see YAML used for any configuration I know I’m in a frustrating time. It’s particularly bad for build systems where there the feedback time can be so slow.

Re: Pkl, a Programming Language for Configuration

#42

Post by avianlyric » Sat, Feb 03, 2024, 11:57 AM UTC

HexDecOctBin wrote: post #36

I'm sorry, can someone explain why one would want to translate from one data description language to another (Pkl -> JSON, or whatever)? Why not just write JSON (or whatever) to begin with?

Because Pkl makes it trivial to write templates and transforms. So you can write a Pkl schema that only requires a minimum set of fields, then auto generate a complete configuration.

This is most useful when dealing with tools like k8s where deploying a single application might involve 3-10 separate manifests (Deployment, Service, NetworkPolicy, HttpRoute, Autoscaler etc etc). With Pkl you can easily write a simple template that only requests the minimum needed to define an “app” (e.g. name, namespace, mixins for sidecars) and have Pkl generate all the needed manifests for you.

Really Pkl should be seen as a language for quickly building templating tools like Helm. But with type safety by default, and no need for horrible indent hacks.

Re: Pkl, a Programming Language for Configuration

#43

Post by pjerem » Sat, Feb 03, 2024, 11:57 AM UTC

HexDecOctBin wrote: post #36

I'm sorry, can someone explain why one would want to translate from one data description language to another (Pkl -> JSON, or whatever)? Why not just write JSON (or whatever) to begin with?

Just scroll a little further. It’s not just another syntax for config files.

Re: Pkl, a Programming Language for Configuration

#44

Post by hiAndrewQuinn » Sat, Feb 03, 2024, 11:57 AM UTC

HexDecOctBin wrote: post #36

I'm sorry, can someone explain why one would want to translate from one data description language to another (Pkl -> JSON, or whatever)? Why not just write JSON (or whatever) to begin with?

Well, Dhall provides something between JSON and a Turing complete language that can make a lot of configuration much quicker to write, if you can hack the functional syntax. Pkl is probably a similar concept.

http://dhall-lang.org/

Re: Pkl, a Programming Language for Configuration

#45

Post by sgt » Sat, Feb 03, 2024, 11:57 AM UTC

Looks great. Reminds me a bit of HCL.

Re: Pkl, a Programming Language for Configuration

#46

Post by lclarkmichalek » Sat, Feb 03, 2024, 11:58 AM UTC

In a competition with sky/starlark, I feel skylark would win here. “Safe subset of python” is what a lot of people presented with this problem want, and skylark gives them almost exactly that.

OTOH, curious to see what advantages Pkl gains from not having the constraints of maintaining familiarity with another language.

Re: Pkl, a Programming Language for Configuration

#47

Post by andrewstuart » Sat, Feb 03, 2024, 11:58 AM UTC

Anything development related from Apple is inherently disinteresting unless it's aimed at Apple, is for Apple and you're building for Apple.

Apple has done nothing cross platform or open source or community oriented so if they come out with something that's intended to be more general is has no base, no users, no audience of non-Apple developers to land on.

I'm not anti Apple - I love MacOS and Apple is my main machine. I'm just pragmatic about Apple technologies - they are all for usage inside the Apple bubble.

Re: Pkl, a Programming Language for Configuration

#48

Post by mirekrusin » Sat, Feb 03, 2024, 11:58 AM UTC

DrNosferatu wrote: post #30

So Apple just invented NixOS?

no

you can click it, it'll open link in your browser where you can read what it refers to.

Re: Pkl, a Programming Language for Configuration

#49

Post by isodev » Sat, Feb 03, 2024, 12:00 PM UTC

HexDecOctBin wrote: post #36

I'm sorry, can someone explain why one would want to translate from one data description language to another (Pkl -> JSON, or whatever)? Why not just write JSON (or whatever) to begin with?

In general (not just limited to Pkl), I think the advantage is that you get IDE support like autocomplete and compile time checks. Pkl seems to borrow some features from JSONSchema/SHACL for example where one can also add validations like "value must be bigger than 20 and lower than 100" so when you configure a component incorrectly, it can throw a good error message before deployment.

Re: Pkl, a Programming Language for Configuration

#50

Post by viraptor » Sat, Feb 03, 2024, 12:01 PM UTC

HexDecOctBin wrote: post #36

I'm sorry, can someone explain why one would want to translate from one data description language to another (Pkl -> JSON, or whatever)? Why not just write JSON (or whatever) to begin with?

Json lacks comments, templating, evaluation, types, and lots of other features. Having something generating a valid config is great, especially if you're generating multiple configs in different format from the same place. For example being able to configure SSH, nginx and some other services from nixos config is amazing.