CLU is the most influential programming language you've never heard of. Many of the basic features of modern programming languages -- such as call-by-sharing, iterators and thrown errors -- first appeared in CLU. How was it made? Why is it so influential? And why isn't it part of our hacker mythology? Let's delve into the history behind CLU and its creator, Barbara Liskov, and discover how this little-known language casts such a long shadow.
The title is a reference to this oft-quoted comment on rock history:
My reputation is far bigger than my sales. I was talking to Lou Reed the other day, and he said that the first Velvet Underground record sold only 30,000 copies in its first five years. Yet, that was an enormously important record for so many people. I think everyone who bought one of those 30,000 copies started a band! So I console myself in thinking that some things generate their rewards in second-hand ways.
Much as the Velvet Underground was much more influential on other musicians than it was heard by general audiences, CLU has been similarly influential with programming language designers than used by programmers. CLU is still influential on programming language design, both Chris Lattner (Apple) and Joe Duffy (Microsoft) cite it in their recent work.
Also, I hint at this in the abstract, but this is specifically a reaction to the folkloric nature of popular computer science history. My own entry into the world of computing history comes from the Jargon File/Hacker Dictionary, one of the largest and best known lexicons of hacker history and culture. Yet its woefully incomplete -- the picture of hacker culture it paints is a combination of MIT during the minicomputer era with Eric Raymond's particular interests & prejudices thereafter. Our culture is far broader than the story Eric Raymond tells; I want to show people like myself the world outside of that bubble.
For your information, there is a 1977 copy of CLU which runs on ITS.
So was mine. Which perhaps explains why I'm so obsessed about ITS now.