It’s taken me a while to get to this talk. Not because it was uninteresting, just because it sent my mind in so many directions that I needed time to collect my scattered thoughts.
Objects and Lego Blocks
On Thursday, James Noble delivered a Keynote about "The Lego Hypothesis". As you might guess, he was talking about the dream of building software as easily as a child assembles a house from Lego bricks. He described it as an old dream, using quotes from the very first conference on Software Engineering… the one where they utterly invented the term "Software Engineering" itself. In 1968.
The Lego Hypothesis goes something like this: "In the future, software engineering will be set free from the mundane necessity of programming." To realize this dream, we should look at the characteristics of Lego bricks and see if software at all mirrors those characteristics.
Noble ascribed the following characteristics to components:
- More similar than different
- Abstract encapsulations
- Coupled to a few, close neighbors
- No action at a distance
(These actually predate that 1968 software engineering conference by quite a bit. They were first described by the Greek philosopher Democritus in his theory of atomos.)
The first several characteristics sound a lot like the way we understand objects. The last two are problematic, though.
Examining many different programs and languages, Noble’s research group has found that objects are typically not connected to just a few nearby objects. The majority of objects are coupled to just one or two others. But the extremal cases are very, very extreme. In a Self program, one object had over 10,000,000 inbound references. That is, it was coupled to more than 10,000,000 other objects in the system. (It’s probably ‘nil’, ‘true’, ‘false’, or perhaps the integer object ‘zero’.)
Lots of other systems in our world form scale-free networks with power law distributions:
- City sizes
- Earthquake magnitudes
- Branches in a roadway network
- The Internet
- Blood vessels
- Galaxy sizes
- Impact crater diameters
- Income distributions
- Books sales
One of the first things to note about power law distributions is that they are not normal. That is, words like "average" and "median" are very misleading. If the average inbound coupling is 1.2, but the maximum is 10,000,000, how much does the average tell you about the large scale behavior of the system?
(An aside: this is the fundamental problem that makes random events so problematic in Nassim Taleb’s book The Black Swan. Benoit Mandelbrot also considers this in The (Mis)Behavior of Markets. Yes, that Mandelbrot.)
Noble made a pretty good case that the Lego Hypothesis is dead as disco. Then came a leap of logic that I must have missed.
"The ultimate goal of computer science is the program."
You are assigned to write a program to calculate the first 100 prime numbers. If you are a student, you have to write this as if it exists in a vacuum. That is, you code as if this is the first program in the universe. It isn’t. Once you leave the unique environs of school, you’re not likely to sit down with pad of lined paper and a mechanical pencil to derive your own prime-number-finding algorithm. Instead, your first stop is probably Google.
Noble quotes Steven Conner from the Cambridge Companion to Postmodernism:
"…that condition in which, for the first time, and as a result of technologies which allow the large-scale storage, access, and re-production of records of the past, the past appears to be included in the present."
In art and literature, postmodernism incorporates elements of past works, directly and by reference. In programming, it means that every program ever written is still alive. They are "alive" in the sense that even dead hardware can be emulated. Papers from the dawn of computing are available online. There are execution environments for COBOL that run in Java Virtual Machines, possibly on virtual operating systems. Today’s systems can completely contain every previous language, program, and execution environment.
I’m now writing well beyond my actual understanding of postmodern critical theory and trying to report what Noble was talking about in his keynote.
The same technological changes that caused the rise of postmodernism in art, film, and literature are now in full force in programming. In a very real sense, we did it to ourselves! We technologists and programmers created the technology—globe-spanning networks, high compression codecs, indexing and retrieval, collaborative filtering, virtualization, emulation—that are now reshaping our profession.
In the age of postmodern programming, there are no longer "correct algorithms". Instead, there are contextual decisions, negotiations, and contingencies. Instead of The Solution, we have individual solutions that solve problems in a context. This should sound familiar to anyone in the patterns movement.
Indeed, he directly references patterns and eXtreme Programming as postmodern programming phenomena, along with "scrap-heap" programming, mashups, glue programming, and scripting languages.
I searched for a great way to wrap this piece up, but ultimately it seemed more appropriate to talk about the contextual impact it had on me. I’ve never been fond of postmodernism; it always seemed simultaneously precious and pretentious. Now, I’ll be giving that movement more attention. Second, I’ve always thought of mashups as sort of tawdry and sordid—not real programming, you know? I’ll be reconsidering that position as well.