People tend to solve problems by producing and manipulating symbolic expressions representing pieces of solutions. They solve problems by translating them into massive arithmetic problems, then grind them down by performing millions of blinding fast computations. This made LISP a natural language for expressing symbol processing, and it quickly gained a loyal following among Artificial Intelligence researchers. Today LISP is still the language of choice for most Artificial Intelligence applications. A language is stable if there is wide spread agreement among its users about what features are part of the language.
Stability is achieved through an official or semi-official description of the language.
Unfortunately, major differences between LISP dialects developed soon after it was introduced. Eventually programs written in one dialect wouldn't run using an interpreter for another. Some of the most popular dialects are shown in the diagram below. Arrows indicate which dialects influenced others. In 1980 work began on a standard dialect called Common LISP .