Almost everybody has their own lisp implementation. Some programmers’ dogs and cats probably have their own lisp implementations as well. This is great, but too often I see people omit some of the obscure but critical features that make lisp uniquely wonderful. These include read macros like #. and backreferences, gensyms, and properly escaped symbol names. If you’re going to waste everybody’s time with yet another lisp, at least do it right damnit.