Apple Pkl

Dhall seems to be explicitly total (non-turing complete) while Pkl seems to be Turing Complete, hence dangerous as you can basically compute anything

The tutorial is also nicely written. Props to Apple for writing really good docs on this one! The error messages it produces also look pretty good.

It would be nice if they added compiled equivalents of each code snippet from the tutorial in other formats, though, since it wasn't immediately clear how certain types (like `duration: Duration = 30.min`) would be represented in JSON.

If anyone at Apple is reading this, another thing that would make it much easier to evaluate and decide whether to adopt pkl would be to include an online compiler with a few built-in examples so that anyone can quickly see how the configuration is transformed without delving into the full docs.

The big gotcha is it's only implemented in Java. So any language bindings have to shell out to a subprocess to actually do any work.

I haven't had a chance to use it yet, but it addresses some gaps in validation for JSON, YAML and other configuration files and I appreciate their approach to the problem. I look forward to using it the next time I have a system with JSON that's unwieldy.

Yeah that looks pretty useful.

In JavaScript land, I just do this with zod to crash the server on startup, but I can't remember if there's already an easy way to do it with the java/kotlin/gos

Start with YAML/JSON/TOML, but then add:

- Optionally strict typing and structs

- Inheritance

- Dynamically computed properties

- Functions & object methods, which are really more like computer properties

- If/Else conditionals, which are really more like a ternary

.. and managed to do it while still making it look like a simple config file.

The closest analogue from memory might actually be Terraform.

The one thing that had me squinting was the object extension syntax. It looks powerful.. and I understand its value.. but wow that's ends up being eye-full of () {} and [] all in one code bock.