Don't say "no"!
Lisp is for the mediocre programmer, too.
(Based on my posting <2T2radg3IosmNv8firstname.lastname@example.org>)
Every now and then I read a Usenet posting or blog entry about the somewhat frightening question from management: "Will someone else be able to work on your Common Lisp code?"
Then most people explain why they had to say "no".
You all know the reasons why they think they have to give this answer. But are the reasons really valid?
I don't think so. It is the job of a programmer to work with different tools. Programming languages are such tools, among others. It is expected that a Java programmer can learn the Eclipse IDE within a few days even if he was a long time user of Netbeans. A programmer has to use many tools he wouldn't choose by himself. Do you think most of them really like writing their e-mails at work with Outlook? :-)
Common Lisp is one of the tools that are available. If you think it fits the task at hand then use it. Chances are good you are no wizard, guru, demi-god. Just a person who does his job. You were able to learn Common Lisp and so should be someone who doesn't have to go through the initial phase of a project in a new language. Everyone following you has better and more books, more libraries, a bigger community — Common Lisp has gained a nice momentum and more and more people use it just for fun and for work. Everyone following you can rely on your code. It is very easy to test and fool around with single functions of your program.
Common Lisp is for the mediocre programmer, too. A programmer bitching about the parentheses and refusing to learn something new or different, isn't a mediocre programmer. He is a bad programmer and a very bad employee. Who wants to employ someone who doesn't want to learn for and on the job? The manager/boss who asks you if someone can pick up or support your work when you choose Common Lisp is the same one who expects his staff to be flexible.
"No, I don't think anybody can be as good and flexible as me." is the answer you give when you say "no".
You all know the essays and rantings of Common Lisp users about how wonderful the language is and that you must one of the top programmers choosing it. They are wrong. All it takes is to be a programmer. Even if you are just mediocre.
OK, some programmers who just do their job don't learn programming languages just for fun. They don't have to be bad ones. Just the typical worker who doesn't want to be bothered with work related stuff after a day's work. It's sad but there are such people in every profession. But it's no reason to believe these people aren't able to learn Common Lisp just because they haven't thought of it themselves.