Rich Hickey "thinks in lisp". For example, he talks about his "maps" data structure (aka association lists). See https://www.youtube.com/watch?v=aSEQfqNYNAc

Since data and programs are the same thing in lisp you can fluidly shift from one to the other, like I did with "knowledge" vs "rules". They both have the same representation (defstructs) but they are also code and have execution semantics. Clojure allows you to do this with map objects.

The fact that you can use the whole language on everything at any time and that everything at any time is also "the language" is how you "think in lisp". Nobody thinks of Python programs as "data" or data as Python programs.

Watch anything Rich Hickey talks about. He really "gets it".