I admit my hastily written example is clumsy, but the general idea still holds in your rendering of it.<p>Nesting with commas is just as confusing as nesting with parenthesis. It forces your reader to operate with more than one contexts at a time, and this is exactly what pushes up the complexity level.<p>Even in Lisp, I realised that I always tend to build flat DSLs instead of the nested, using the non-parenthesised punctuation wherever possible. And I am not alone, take a look at the LOOP macro for example.