That's what Common Lisp itself is: one Lisp to rule them all. And it actually works pretty well. There are libraries that work across a wide variety of CL implementations.
Yeah, but then there are some schemes and racket and Janet and picolisp and so on too. Then there are different CL implementations right (e.g., Allegro, SBCL, that old one the barski book recommends...etc). Too many implementations and not enough users I guess.
