SF You never walk in the same river, otherwise known as Strachey streams.
AK The user interface, which is still the predominant approach today, is a user interface as the access to function. If the area is interesting, you eventually wind up with something that looks like the control panel of a nuclear reactor. So this is the agglutination of features.
SF Yes, a button on every pixel.
AK Corporate buyers often buy in terms of feature sets. But at PARC our idea was, since you never step in the same river twice, the number-one thing you want to make the user interface be is a learning environment—something that’s explorable in various ways, something that is going to change over the lifetime of the user using this environment. New things are going to come on, and what does it mean for those new things to happen?
This means improvements not only in the applications but also in the user interface itself. Some of those ideas were quite manifest in the original Macintosh, but are much less manifest in the Macs of today—and of course never really made it to Microsoft. That just wasn’t their way of thinking about things, and I think a programming language is the same way. Even if the user is an absolute expert, able to remember almost everything, I’m always interested in the difference between what you might call stark meaning and adjustable meaning.
I did quite a bit of study on that over the years to understand the influence of having something that you can read. It’s known that our basic language mechanism for both reading and hearing has a fast and a slow process. The fast process has basically a surface phrasal-size nature, and then there’s a slower one. This is why jokes require pauses; the joke is actually a jump from one context to another, and the slower guy, who is dealing with the real meanings, has to catch up to it.
There have been many, many studies of this. This argues that the surface form of a language, whatever it is, has to be adjustable in some form.
SF As you probably know, recent research has looked at how different parts of the brain recognize and react to jokes. Physically, they are quite distinct.
AK Yes. All creativity is an extended form of a joke. Most creativity is a transition from one context into another where things are more surprising. There’s an element of surprise, and especially in science, there is often laughter that goes along with the “Aha.” Art also has this element. Our job is to remind us that there are more contexts than the one that we’re in—the one that we think is reality.
In the ’60s, one of the primary goals of the computer science community was to arrive at an extensible language. As far as I know, only three ever actually worked, and the first Smalltalk was one of those three. Another very interesting one was done by Ned Irons, who invented the term syntax-directed compiler and did one of the first ones in the ’60s. He did a wonderful extensible language called Imp.
One of the things that people realized from these extensible languages is that there is the unfortunate difficulty of making the meta-system easy to use. Smalltalk-72 was actually used by children. You’re always extending the language without realizing it when you are making ordinary classes. The result of this was that you didn’t have to go into a more esoteric place like a compiler compiler—Yacc or something like that—to add some extension to the language.
But the flip side of the coin was that even good programmers and language designers tended to do terrible extensions when they were in the heat of programming, because design is something that is best done slowly and carefully.
"A Conversation with Alan Kay," Programming Languages, Vol. 2, No. 9 - Dec/Jan 2004-2005.
