There was a "mock" mathematica a few years ago called "mathomatica" which was the mathematica language implemented in common lisp (if I recall correctly). It was a pleasure to use and a drop-in replacement of the language (but not for all the standard library of functions). Unfortunately, they god bullied to death and its trace is almost gone. The author just wanted to prove a point "you are so damn crazy by that silly language that anybody can re-implement in a few hundred lines of lisp", and once his point was proven he did not want to pursue it any further. And here we are.

EDIT: got some names wrong, here's a possible starting point for this rabbit hole https://def.fe.up.pt/pipermail/maxima-discuss/2009/029211.ht...