[bioballer]

I think this is a reasonable approach if you only have one stack, and don't have a lot of config. If you have one stack, you can put all the validation, types, and everything else in your runtime application, and then you don't need to learn new languages, and everything works.

This becomes a lot more painful if your work is more polyglot. If you need to define config that needs to be shared between different applications, but they're written in different languages, you'll have a much harder time. Also, say, if you need to deploy your applications to Kubernetes, and your Kubernetes specification needs to provide config files to your application, then you'll still end up in a situation where your statically typed programming language won't help. That is where something like Pkl becomes really helpful, because you have just one place to manage all that complexity--right in Pkl itself.