JSON, YAML, or XML, it's all the same crap. The fact that programmers are feeling the need to externalise their business logic into "config" files is a sign that the language has failed. In a decent language you would write logic or "config" in the language itself, because the language would be a comfortable medium for expressing things (this is the norm in Python for example - while a few overengineered pieces insist on using TOML or something, most Python libraries don't require any separate config, you just "configure" them the same way you do the rest of your programming, in Python).