drakecoffeecake

Yep, yep, yep.

You seem to be exactly right.

I don't think that's much clearer than a lisp equivalent:

    (todo "housework"
        (item (priority high) "Clean the house.")
        (item (priority medium) "Wash the dishes.")
        (item (priority medium) "Buy more soap."))

Yours looks nicer, but if I wanted to operate on your todo there, it's not obvious how just by looking.

With the lisp, it's obvious: There's a list of 5 elements. The last three are 'items', each of which is a list of 3 elements.

The benefit of s-expressions isn't just that they're flexible in what you can write with them, but that they're easy to manipulate programmatically, and their structure is immediately obvious.

Lisps let you define the semantics and syntax of a form with macros. I would consider the loop macro in CL to have an internal DSL.

--edited