Explore apple/pkl support

[bradenhilton]

https://pkl-lang.org/ • Integration with Go • https://github.com/apple/pkl • https://github.com/apple/pkl-go-examples

I suspect this will inevitably come up as/when it grows in popularity.

Some ideas off the top of my head:

• Using pkl for .chezmoi*.$FORMAT files
• Offering pkl's generation functionality and/or possibly pkl unmarshalling as template functions, e.g.:

  {{ toPklJson "config.pkl" }}
  {{ fromPkl "config.pkl" | toJson }} etc.

  so that config files can be stored in the source state as .pkl files and benefit from pkl's validation/error checking, while also being rendered in the appropriate format in the target state

[halostatue]

If it already had support for TS/JS and Elixir, I would be using it for a current work project, despite it being so new to the rest of the world.

One thing to be aware of about pkl is that it is a Turing-complete language, so it is not a perfect fit for how chezmoi sees its configuration files. But it is very exciting (IMO).

[twpayne]

I'm not sure if this is the right fit for chezmoi.

Pickle looks fantastic for complex configuration needs, as does CUE, which solves a similar problem and a bunch of awesome Gophers work on. However, chezmoi's configuration is pretty simple and user-facing so maybe the current JSON/TOML/YAML config options are enough.

I would definitely support adding Pickle template functions, for example the proposed toPklJson and fromPkl, but I would like to hear support from users with problems that can only be solved by using Pickle before adding this.

[twpayne]

Let's wait for reported use cases for Pkl support. For now, I'll close this as "not planned".