Which is just as effective an argument against the entire of SICP. In a real lisp, a (list? <some-fn>) doesn't return true. You can't dig around inside a closur

Which is just as effective an argument against the entire of SICP. In a real lisp, a (list? <some-fn>) doesn't return true. You can't dig around inside a closure and walk the entire environment which is made up of a list of pairs. But the point of a toy model is that you can read an implementation, build your own, reason about it and send code through it with little difficulty. Once you've built eval and sent real programs through it, it's not a big jump from that to understanding how real tools work, which can generally be done incrementally. That was certainly my lisp journey, and that includes macros (which were a separate step). After implementing them in eval, learning how they're in the real world was about as challenging as reading a restaurant menu.