I suggest “Lisp in Small Pieces” as a great introduction to implementing a Lisp. It focuses on Scheme rather than CL, but all of the knowledge is transferable.

I suggest “Lisp in Small Pieces” as a great introduction to implementing a Lisp. It focuses on Scheme rather than CL, but all of the knowledge is transferable. In the book, you go through multiple basic implementations, each successively more sophisticated, starting with basic interpretation and moving through more optimizations toward a compiler.