NestedText, a nice alternative to JSON, YAML, TOML
You know what I want? Schemas. And clear error messages.<p>I want to know beforehand what I can put in a config file and I want a fast and hard failure if what I put in there is not good.<p>And this should be implemented at the file format parser level, with hooks for apps to add on top of the default behavior, so that every app that implements this format gets these things almost for free.