I liked what I saw of Pkl, wanted to use it when it was released but it seemed the only parser was JVM-based and it was intended more to be transpiled into other config languages. If that's changing definitely worth revisiting it. Dhall I had to look up, it seems nice as long as the formatting used on website examples is not enforced, because to me that looks like an absolute nightmare but my problems are with the whitespace and not the structure itself.