We are using different notions of type. For me, a type is a static guarantee about the meaning of a syntactic term in the program, rather than a mere labelling

We are using different notions of type. For me, a type is a static guarantee about the meaning of a syntactic term in the program, rather than a mere labelling of values during the runtine process. In the sense of type that I use, Common Lisp does not have but just one type, and it is not even a type of numbers - it is a type of everything. All in all, I did not intend to overly diss Common Lisp. It is a very flexible, expressive and powerful language. I am just saying that, at least from my point of view, Common Lisp does not look particularly inspired by mathematics.