Mark, you're a polyglot. I would say for the last 20 years you have been a C++, then Java author more than a Lisp programmer.

The first C++ book I ever owned was yours, the one about artificial agents that had a sculpture on the cover, and that must have been 15 years ago.

If you're in the business of education, your "toolbox" is essentially whatever people need to learn. You wouldn't hear an English teacher in Korea with 25 years of experience saying she is done teaching English, because teaching Spanish is so much more easier. That doesn't make any sense. At the time you wrote the published Lisp books, it was the height of AI-bubble and people needed to learn Lisp and Prolog. Then you wrote an Smalltalk book (IIRC.) then C++, Java .. all dictated by what the public needed.

Btw, you still have the literary and expository prowess to teach today's hot technologies as well. But that doesn't say anything about Lisp, Prolog, Smalltalk, C++, or Java except that you are no longer in the business of teaching them.

And I mightly thank you for the Agents book, btw. I didn't know what I was doing and just typed in the code into Borland C++ 4.5. The diskette was missing when I bought it, and I am sure I tried to download the source code from the Addison-Wesley ftp site (it could have been a Prentice Hall book as well)

Cheers!

I must admit that I usually think that whatever projects that I happen to be working on are: most fun, most interesting, etc. Same comment applies to programming languages, tools, and frameworks. This is a reflection of a simple fact of life: whatever we think hard about and generally mull over, becomes very interesting.

> Ruby has mostly replaced Lisp in my toolbox.

Wow. Would love to hear why. Could you list some of your weighted plusses and minuses for Lisp and Ruby?

I used to worry more about good runtime performance. Now I prefer to use a language that is easier and faster to use in development.

re: pluses and minuses:

Lisp:

+ better interactive development style; I'll keep a Lisp repla open most of the day. For Ruby, irb is not something that I live in.

+ really great runtime perfromance

- not as many libraries for web frameworks, database, etc.

Ruby:

+ very concise and fun to develop with

+ many great libraries and frameworks

- poor runtime performance

That said, I am likely to be using Lisp a lot next year: I have a partially written book on Franz AllegroGraph that the people at Franz suggested that I put on hold until their new version 4 is released. The free version of AllegroGraph is awesome (supports 50 million RDF triples, and easily used from Lisp, Java, Ruby, Python, etc. clients). The $$ version scales very well to huge data sets.