First off lisp does have state. It isn't a pure language. That aside there are several approaches. The easiest is to thread state that is have a function that

First off lisp does have state. It isn't a pure language. That aside there are several approaches. The easiest is to thread state that is have a function that looks like update Worldstate = do userinput <- getUserinput; Worldstate' <- updateworldstate userinput worldstate; drawworldstate worldstate'; update worldstate';