I have been reading a bit about Common Lisp and I am considering trying to learn it (I only know very basic concepts) or even using it for some project.
Question: how stable is Common Lisp as a language? What I mean is, regardless of new libraries, are new language features (involving new syntax and semantics) being added to the language? In other words, if I learn Common Lisp now, would I be able to use the same language in 10 years from now, or read code that was written 10, 20 years ago (apart, of course, from having to get familiar with different libraries and API's)?
Best Answer
There is the ANSI Common Lisp standard and the Common Lisp Hyperspec. It's generally reasonable to assume that standardised languages will stay relatively stable and that most new language additions will be consistent with the standard / not break existing code.
Of course, one of the powers of Lisp is that you can extend the language almost arbitrarily, so there's quite a possibility that some new libraries or DSLs will look completely different from any other previous Lisp code. That's just a danger of the meta-programming territory. But the core language itself is likely to stay pretty stable.
If you are interested in Lisps in general as opposed to Common Lisp specifically, I'd also recommend you check out Clojure (a modern, pragmatic, functional Lisp) and Scheme (a very clean, elegant Lisp ideal for learning).