"I have a mind like a steel... uh... thingy." Patrick Logan's weblog.

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Friday, March 25, 2005

Alan Kay (again) on Software Engineering

Kay's interview has made the rounds more than once, but with recent posts on software as engineering or craft, let's go back to the guru...

If you look at software today, through the lens of the history of engineering, it’s certainly engineering of a sort—but it’s the kind of engineering that people without the concept of the arch did. Most software today is very much like an Egyptian pyramid with millions of bricks piled on top of each other, with no structural integrity, but just done by brute force and thousands of slaves...

I would compare the Smalltalk stuff that we did in the ’70s with something like a Gothic cathedral. We had two ideas, really. One of them we got from Lisp: late binding. The other one was the idea of objects. Those gave us something a little bit like the arch, so we were able to make complex, seemingly large structures out of very little material, but I wouldn’t put us much past the engineering of 1,000 years ago...

I finally understood that the half page of code on the bottom of page 13 of the Lisp 1.5 manual was Lisp in itself. These were “Maxwell’s Equations of Software!” This is the whole world of programming in a few lines that I can put my hand over...

All of these ideas could be part of both software engineering and computer science, but I fear—as far as I can tell—that most undergraduate degrees in computer science these days are basically Java vocational training...

In a history of Smalltalk I wrote for ACM, I characterized one way of looking at languages in this way: a lot of them are either the agglutination of features or they’re a crystallization of style. Languages such as APL, Lisp, and Smalltalk are what you might call style languages, where there’s a real center and imputed style to how you’re supposed to do everything. Other languages such as PL/I and, indeed, languages that try to be additive without consolidation have often been more successful. I think the style languages appeal to people who have a certain mathematical laziness to them. Laziness actually pays off later on, because if you wind up spending a little extra time seeing that “oh, yes, this language is going to allow me to do this really, really nicely, and in a more general way than I could do it over here,” usually that comes back to help you when you’ve had a new idea a year down the road. The agglutinative languages, on the other hand, tend to produce agglutinations and they are very, very difficult to untangle when you’ve had that new idea.

One clear implication is that language you use has a significant impact on your ability to do software engineering. Your language is your most highly used tool.

5 comments:

Considered Opinion said...

Let us not forget the ability to use other people's code.

This is just about my only complaint with current implementations of Lisp, Scheme and Smalltalk. They are beautiful languages. And they have all but dismissed the commercial component market.

Patrick Logan said...

I think that is a fair comment. They've been better at being consumers of other components than providers.

I'd rather criticize the major vendors of tools for component building for not recognize the value of these languages. But that's my perspective and won't necessarily gain sympathy from VB or Java developers building components for their markets.

phil jones said...

The "plays well" with other programs / components / OS features is a bit orthagonal to this, no?

C, should be considered a "style" lanaguage. Rather than an "agglutination" language. And it plays well with the outside world.

Smalltalk and Lisp suffer from having been early exponents of managed code at a time when the OS wasn't ready for such things.

I wonder how easy it will be to run them on Parrot ...

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Portland, Oregon, United States
I'm usually writing from my favorite location on the planet, the pacific northwest of the u.s. I write for myself only and unless otherwise specified my posts here should not be taken as representing an official position of my employer. Contact me at my gee mail account, username patrickdlogan.