One main thing that one gets for free this way is garbage collection. I once started writing a lisp iterpreter in C++ but that kind of fell by the wayside once

One main thing that one gets for free this way is garbage collection. I once started writing a lisp iterpreter in C++ but that kind of fell by the wayside once I realized that it is quite easy to create cyclical references in lisp and then using shared_ptr is not good enough.