It's striking how many of the responses are just trying to flex their knowledge of FP. The real answer is that Common Lisp is not a pure functional language. M

It's striking how many of the responses are just trying to flex their knowledge of FP. The real answer is that Common Lisp is not a pure functional language. Many CL idioms involve mutation, the most obvious one being setf. So, it manages it like Python or JavaScript manages, by not managing it.