Not necessary that "indented" lisp breaks code==data property. Just like YAML can represent an arbitrary tree structure, indented syntax can be mapped to S-exp

Not necessary that "indented" lisp breaks code==data property. Just like YAML can represent an arbitrary tree structure, indented syntax can be mapped to S-expr and vice versa. I suspect the reason that alternative syntax for Lisp doesn't fly is that, once you use Lisp enough, you start feeling too comfortable with S-expr and the editor's support on it to switch to alternative syntax. It only appeals to those who are new to the language. And the downside is that the editor support can't be as good as S-expr (I suppose; is python-mode capable of various C-M-something tricks?).