Lambda the Ultimate

Maybe everybody shall just write a book about all the languages he likes. Than we have far more authors and less readers. But who cares?

Ew. The only thing you can possibly get from a book full of languages that the author only put in because he likes them is a lot of stuff that you will probably disagree with. :)

Completely agreed. I'm of the opinion that OOP in languages like C++ and Java is an entirely different subject than OOP in Smalltalk and Ruby.

It seems that you're not alone in that opinion. Here's a quote from Alan Kay's keynote speech at OOPSLA 1997 (available via Google Video here - the comment in question appears roughly 10 min 30 sec into the speech):

...I made up the term object-oriented — and I can tell you I did not have C++ in mind...

Lest we take that quote to imply satisfaction with Smalltalk, Alan Kay has also said:

"Perhaps it was commercialization in the 1980s that killed off the next expected new thing. Our plan and our hope was that the next generation of kids would come along and do something better than Smalltalk around 1984 or so. We all thought that the next level of programming language would be much more strategic and even policy-oriented and would have much more knowledge about what it was trying to do. But a variety of different things conspired together, and that next generation actually didn’t show up."

Cat has a type system, which sets it apart significantly from Forth and Joy.

I must admit that I have no knowledge of research on the subject (I'm sure it's been done - I just don't know anything about it), but in my experience there seems to be at least two general schools of thought on the process of learning/teaching: 1) slow and steady, 2) sink or swim. The idea of putting a lot of languages in the same book and throwing stuff at the student left and right is approach #2. Most books use approach #1. I think it's just different is all - unless there's solid research proving it's a bad idea (links welcome!), I say more power to him! :-)

A lot of research besides the fact that it's harder learning multiple things at once?

:-) Since I have no research knowledge to point to or even really guess about, I'll just wrap up my opinion of this matter thusly: What does it hurt for him to try it his way? In my own experience I've had times when I wanted to strip away complexity and try to learn from base principals and other times when it seemed better to just jump in and try to understand not only the problem area itself, but the context surrounding it.

My only experiences with programming text books have been the slow, methodical approaches of one overall language, one language feature per chapter, etc. After plowing through all the way to the end you may have a great new set of words and terms in your head but no immediate sense of how it all fits together and why. Perhaps by teaching programming through multiple languages a student could begin to form a larger picture in their head that transcends just learning the steps into an understanding of why the steps exist in the first place.

Even if I set all of my baseless emotional opinion aside, there's still the reasonably undeniable fact that in this age of Web 2.0 (ack), building even a simple web application can involve a host of different languages from SQL, to PHP, to Javascript, HTML , and CSS. People don't seem to have just too much trouble learning what they need to know when they are driven to accomplish a goal. If the goal is to learn why programming works, what it is, and how to best apply it - perhaps a multi-language text book is a legitimate answer and could help avoid religious devotion to any single language simply because so much time was spent learning it instead of learning general principals.

My only experiences with programming text books have been the slow, methodical approaches of one overall language, one language feature per chapter, etc.

That's not what I said. My point was to pick one language that will stay out of the way and will let you focus on whatever concept (*not* a syntactical language feature) that you want to cover in the given chapter. So with Python, for example, you can go from procedural to OO (incl. multiple inheritance and mixins), with a sprinkling of functional (list comprehensions, map, filter, etc.) in between. Use Stackless Python and you can cover coroutines and concurrent programming, too.

CTM has a similar approach but uses Oz as the language. I think using Python or something similar would give a very different feel to the course, a bit more "relaxed" and forgiving I think. (Call it the European vs. North American approach. :-)

Before writing any textbook, one has to address the target audience. Are these freshmen in high school, freshmen in college, post-graduate students, or somewhere inside or outside of that spectrum. Next question is what level of knowledge one assumes about programming - are these people that have never touched a computer? Have they ever written a program? Are they proficient in one or more languages?

And then there's the motivation for what the text wishes to accomplish. Does the text want to have an impact on people who are only mildly interested in programming. Are you aiming at the self-motivated kids that have hacked on computers since they were in diapers. Are you aiming at the professional programmer? Are you aiming at the theoreticians?

Or to summarize, a textbook writer has to make assumptions about the students. What assumptions one makes about the students will determine the tone and depth of the text. A good study of one set of choices aimed at a specific audience of college freshmen is the material surrounding the text "How to Design Programs" (HTDP). Here the authors elected to use a minimalistic language (a restricted subset of Scheme) because the course is not about programing languages - but rather programming. On the other hand, CTM is very much about advanced concepts in programming and the PLs that are used. Those authors chose a subset of Oz and limited forays into other languages.

If I were to go back in time and become a college freshman, I'd probably prefer to use Scheme as the language for my textbook. But then, when I was actually a freshman, I thought I knew everything there was to know about almost any subject - so I probably would have preferred C at that stage in my life (I was so much older then, I'm younger than that now).

Anyhow, if I was to offer advice on the subject to cdiggins, I'd probably say do as much with Cat as possible. First, the subject would be an interesting study in PL design. And second, the author has much more at stake with that particular language - so the care and craft would be much more a labor of love.

I think you make some excellent points Chris, thank you. In fact thank you to everyone who has provided me with useful feedback.

I have come to a clearer understanding of what it is I intend to do, and how to achieve it. What I was describing originally would have been appropriate for several books of material aimed at different levels.

I think that I shall start with a textbook aimed at College Freshaman who haven't neccessarily ever programmed the computer.

I plan on pursuing this in Cat, which may either marginalize the book, or bring Cat into the mainstream. However, as Chris pointed out, it might as well be a labour of love so that I will do my best possible job at it.

Maybe I will attempt a survey of languages and techniques afterwards.

Thanks again everyone!

If you're going to use Cat, then Forth is fantastic for experimenting with how memory works.