apple/pkl ? reverse-engineered prompt

Build me a configuration as code tool that lets people write settings in a simple readable language, then turn those files into JSON, YAML, or other common config formats.

I want the language to support strong validation, reusable pieces, and nice error messages when something is wrong. It should also have a command line app, a parser, a formatter, and basic docs so someone can try it quickly and understand how it works. If it makes sense, include simple examples for defining config for apps and checking that required values are present.

Please keep it polished and usable, not just a demo. Use the current docs online if you need to, and make sure the whole thing is wired together so the language, CLI, and tooling feel like one product.