HOCON is great. It can be incorporated into many programming languages. And it supports inheritance, includes, overriding of environment variables and so on. I

HOCON is great. It can be incorporated into many programming languages. And it supports inheritance, includes, overriding of environment variables and so on. I think that this library found a very good compromise between configuration and programmability. In configuration files you want overrides, includes, comments and inheritance. May be very very simple pattern matching. Yet, you do not want flow control structures such as if-statements/loops & gotos.