I read that, too. But I'm not sure what he means by 'Only lists are by default'. If he means that only lists have a literal representation, then it would be slightly wrong - since Common Lisp has literal representations for various numbers, symbols, characters, strings, vectors, arrays, structures, pathnames, ...

Plus the s-expression syntax is user-extensible - making it as 'homoiconic' as the user needs it.

Interesting, thanks.

I'm referring to the fact that Common Lisp does not have a map and set literal by default. It has a lot of homoiconic literals, and is still very homoiconic. And Common Lisp's reader and printer can be extended by the user to add them back in non standard ways. I still personally consider it as a slight cons against Clojure.