> What?? In chapter 4, you write your own Lisp interpreter. If they had chosen C++, would you be writing a C++ compiler? Or a Lisp interpreter in C++?

That's in chapter 5 :)

Exercise 5.51. Develop a rudimentary implementation of Scheme in C (or some other low-level language of your choice) by translating the explicit-control evaluator of section 5.4 into C. In order to run this code you will need to also provide appropriate storage-allocation routines and other run-time support.