Peter Seibel - Coders at Work - Reflections on the craft of programming

Seibel:So do you think most programmers today, who may be working at a fairly high level, in a different environment would have learned assembly and microcode? Or do you think the kind of talents that people need to be successful programmers are changing?

Ingalls:Yes and no. It is in a way the same up and down at any level and hopefully it will come to appear even more so. But there are areas right now where I think there’s more putting together according to formula and other areas where there’s dealing with things that are much more primitive.

I was a physicist; I had mathematician friends and I did not feel like I was at all the same kind of brain as they were. But we both did good things. I think that’s going to be the case in computers, too. The people who are working on program provers are different from the people who are working on graphics systems, I think. And so people are going to find their strengths and the place they want to work and the place that they’re not comfortable working. I think there’s some nature as well as nurture going on here, and there always will be.

It may be that some of these systems have enough levels and parts to them that a given person may be mainly comfortable and productive working in one kind of area rather than another, but I think it’s all the same stuff. There’s logical thought and there’s structural thought. And there’s human stuff and creativity. A given person has a given mix of that from their nature and their nurture, and to me, it hasn’t changed much. People are trying to do presumably bigger, better stuff, but it seems to me to still be pretty much the same.

Seibel:Related to that, as more and more fields rely on computing in more and more ad hoc ways, there are folks who want to find a way for “nonprogrammers” to program. Do you think that’ll happen, or will domain experts, say biologists, always have to team up with programmers to build custom software to solve their problems?

Ingalls:I think there will be that kind of collaboration because the biologist isn’t interested in programming it. He’s interested in finding out this or that. Then there’s somebody who understands how this stuff is being worked on on the computers who can help him do that. I think the thing that lets a nonprogrammer program is an application.

Seibel:I worked on a project that tried to provide a programming environment for biologists on the theory that the software they would need would always be ad hoc. You couldn’t build an application and be done with it because the biologists didn’t really know what they needed until they got down to some piece of biological data and said, “What I really want to know is X,” and the only way to extract X from that data was, essentially, to write a program.

Ingalls:Yeah, it would be nice if we could have some computing environment with all your information in it so you could somehow figure out how to get to it all just by its self-revealing nature. But I think that there are people who are going to be interested in that and people who aren’t.

Seibel:Is there anything I haven’t asked about that you thought I might?

Ingalls:Often, reading about famous people, the side of it that I’m interested in is, how do they make their life work? All the things that weren’t their passion, and how did they deal with that, and with their family, and with their finances, and balancing that. Or did they just hole up and say, “To hell with everything else,” and let it just come crumbling down until they had their work done?

Seibel:Do you feel like there were times in your life where your passion for programming ran amok to the detriment of other parts of your life?

Ingalls:Yeah, there are times when it’s been hard on others because I’m focused and need to stay focused. It’s a risk with anybody who’s got a passion for what they’re doing. I think either you learn to moderate it somewhat or the other thing you do is communicate it so that everybody around you knows that you’re dealing with this thing, and you’ll probably be done in a week, but until then Daddy’s somewhat inaccessible.

Seibel:And then you win your “Dad the Determined Debugger” award.

Ingalls:Exactly; right. The other thing is, the more you can reflect the satisfaction from progress back out to all the people who have dealt with you during that time, at least they have a sense that Daddy’s doing something good, and we’ll all be happy when it’s done.

A prodigy, L Peter Deutsch started programming in the late ’50s, at age 11, when his father brought home a memo about the programming of design calculations for the Cambridge Electron Accelerator at Harvard. He was soon hanging out at MIT, implementing Lisp on a PDP-1, and hacking on and improving code written by MIT hackers nearly twice his age.

As a sophomore at UC Berkeley, he got involved with Project Genie, one of the first minicomputer-based timesharing systems, writing most of the operating system’s kernel. (Ken Thompson, inventor of Unix and the subject of Chapter 12, would also work on the project while a grad student at Berkeley, influencing his later work on Unix.) After participating in a failed attempt to commercialize the Project Genie system, Deutsch moved to Xerox PARC, where he worked on the Interlisp system and on the Smalltalk virtual machine, helping to invent the technique of just-in-time compilation.

He served as Chief Scientist at the PARC spin-off, ParcPlace, and was a Fellow at Sun Microsystems, where he put to paper the now famous “Seven Fallacies of Distributed Computing.” He is also the author of Ghostscript, the Postscript viewer. In 1992, he was part of the group that received the Association for Computing Machinery Software System Award, for their work on Interlisp, and in 1994 he was elected a Fellow of the ACM.

In 2002 Deutsch quit work on Ghostscript in order to study musical composition. Today he is more likely to be working on a new musical composition than on a new program, but still can’t resist the urge to hack every now and then, mostly on a musical score editor of his own devising.

Among the topics we covered in our conversation were the deep problems he sees with any computer language that includes the notion of a pointer or a reference, why software should be treated as a capital asset rather than an expense, and why he ultimately retired from professional programming.

Seibel:How did you start programming?

Deutsch:I started programming by accident when I was 11. My dad brought home some memo from the Cambridge Electron Accelerator, which was being built at the time. There was a group that did design computations and some memo of theirs accidentally found its way to him. I saw it lying around his office and it had some computer code in it and there was something about it that caught my imagination.

It turned out the memo was actually an addendum to another memo so I asked him if he could lay his hands on the original memo. He brought that home and I said, “Gee, this stuff is really interesting.” I think I might actually have asked him if I could meet the guy who had written the memos. We met. I don’t really remember the details any more—this was 50 years ago. Somehow I got to write a little bit of code for one of the design calculations for the Cambridge Electron Accelerator. That’s how I got started.

Seibel:So that was when you were eleven. By 14 or 15 you were playing on the PDP-1s at MIT, where your dad was a professor.