Well, s-expressions are not Lisp. Not every s-expression is a valid Lisp program. (1 * 2 ^ 3 + 1) is a valid s-expression, but not a valid Lisp program. With a

Well, s-expressions are not Lisp. Not every s-expression is a valid Lisp program. (1 * 2 ^ 3 + 1) is a valid s-expression, but not a valid Lisp program. With an INFIX macro it could be: (infix 1 * 2 ^ 3 + 1) could be a valid Lisp program, with a corresponding infix macro. But the Lisp syntax still is on top of the s-expression syntax...