[jackalope]

Possible improvements occur to me:

1. If indentation is significant and required, dotted notation should be optional:

    [foo]
        [bar]
            [car]

The parser should be able to understand that this results in a foo.bar.car structure without explicitly using dotted notation in the keys.

2. Support include files. With #1 implemented, includes would be extremely powerful and flexible. Since indentation is required, no special syntax is needed to relatively position the included files. And without requiring dotted notation in keys, include files can be reused in a configuration (such as common settings in the [servers] section of the example).