@cdwilson EDN (https://github.com/edn-format/edn), as it supports all the data types I need. And has comments, as opposed to JSON. This is what I use for anything I write.
For the muggles, I'd suggest JSON, even thought it doesn't support comments, and getting the commas just right is finicky. Just stick the comments into extra strings.
@cdwilson Well, in all fairness, I cheated a little: EDN is natural and easy for #Clojure programmers, because it pretty much *is* the Clojure syntax. One could say I write all my code in EDN.
But, it is useful even if you do not use Clojure, and can at least serve as a reference point for what a configuration format should be.
@jrychter @cdwilson else Iβd like TOML
#dhall looks interesting too, but I'm not sure if it's still active. Spago, the #purescript build system, used it, but I think they changed to YAML.