The project was headed by Jon L White,[3] with a stated goal of maintaining compatibility with MacLisp while fixing many of its problems.
"[5] Lisp was used as the implementation of the programming language Micro Planner that was the foundation for the famous AI system SHRDLU.
Lisp, in particular Maclisp (so named because it originated at MIT's project MAC) was also used to implement the Macsyma computer algebra system.
In the 1970s, as AI research spawned commercial offshoots, the performance of extant Lisp systems became a growing problem.
These requirements led to a very aggressive and complex optimization strategy which was applied prematurely, with negative results on the final system.