Lisp is a multi-paradigm language. You can write code as imperatively as you need with it. Use the functional paradigm "by default" and then revert to imperativ

Lisp is a multi-paradigm language. You can write code as imperatively as you need with it. Use the functional paradigm "by default" and then revert to imperative where it makes sense. If you wanted to make a game in Haskell, which is purely functional, then your concerns would be more appropriate.