One of the goals of Common Lisp was backwarts compatibility. The stuff from McCarthy's Lisp is mostly present in Maclisp, Zetalisp and Common Lisp. That's why t

One of the goals of Common Lisp was backwarts compatibility. The stuff from McCarthy's Lisp is mostly present in Maclisp, Zetalisp and Common Lisp. That's why they are Lisp languages. Every language existing for a longer period of time accumulates different design approaches. A language purist may complain, but a programmer will get his stuff ported and will get work done.