Lisp and Smalltalk are dead: It’s C all the way down.

August 14, 2009 at 12:09 pm

Georgia Tech’s College of Computing is now considering a proposal to remove Smalltalk from the required curriculum in favor of C++. When I got here in 1993, we taught Pascal (mostly) and had required courses in C, Lisp, and Smalltalk. The faculty explicitly valued that students see more than one school of programming thought. I took over the Smalltalk-using course from John Schilling and Richard LeBlanc, and moved it from ObjectWorks to Squeak. When we moved to semesters in 1999, Lisp got dropped, and we’d moved from Pascal to Java as our main teaching language. When we drop Smalltalk (now using VisualWorks), we will have a first semester in Python, and the rest of the required curriculum will be Java, C, C++, and C#. We will explicitly tell students “C and C-like languages are all that there is.”

Why drop Smalltalk? Students and teachers view it as “a dead language, not worth learning.” It is the case that there are concepts in Objects and Design (the name of the course) which can most easily be discussed in C++. C++ is wildly popular in industry, so it’s not surprising that some language-specific techniques have developed, techniques that our students should probably know.

It’s reasonable to teach a course on object-oriented analysis, design, and programming in C++ rather than Smalltalk. I’m more disappointed that we will have a curriculum that is all about C.

Richard Gabriel has been thinking a lot about the C-ness of our discipline. If you have not read Richard Gabriel’s articles on “Worse is Better,” I recommend them. Dan Weinreb has a nice overview, and there’s a list of all the various pieces in Gabriel’s debate (some of which was with himself!). Gabriel has been trying to understand why Lisp, despite its many measurable benefits over C (e.g., Lisp programmers are more productive and generate fewer bugs, Lisp environments are amazingly powerful, Lisp code is small and runs fast), has so clearly lost the battle over hearts and minds.

Gabriel contrasts two design philosophies, the MIT/Stanford philosophy (which he calls “the right thing“) and the “New Jersey” C/UNIX philosophy (which he calls “worse is better”). In short form, the MIT/Stanford philosophy (which he associates with Lisp, and which I also associate with Smalltalk) is that correctness and consistency are the most important design quality. In Lisp and Smalltalk, we have S-expressions and objects consistently. The C/UNIX philosophy places simplicity in interface and implementation as the most important design quality.

Python is a mishmash of the two design philosophies. Yes, you get lambda and map/reduce and objects and classes. But you lose the consistency and syntactic flexibility of Lisp and Smalltalk. What’s interesting is that Python, being the least C-like of the popular languages in computing education today, is mostly seen as a language for the NON-computing major. It’s like faculty are saying, “Oh sure, those simpler and more conceptual ways of programming are fine for people who won’t be real programmers. For our students, it’s C all the way.”

I don’t dispute that Unix/C philosophy has won the marketplace. I worry about only teaching that to our students. I think it’s important for Computing majors to understand Gabriel’s debate, to understand what’s valuable about Lisp, Smalltalk, APL, and other high-power, lots-done-in-few-lines-of-code, flexible languages and environments. We want our students to be thought leaders, to think about possibilities that aren’t currently in vogue in the marketplace. They should know about lessons of history, to avoid repeating mistakes and to resurrect old ideas when technology and opportunities fit.

The political forces are lined up to make the Georgia Tech change likely. In comparison with the departments that I had contact with this summer, we’re late. The C-only train has left the station. Few departments teach surveys of programming languages anymore, and I don’t know of any department that teaches a required course in history of computing. I worry about what this means for our discipline. Are we really going to tell students that the peak of human expressibility for computation was in 1973? That all programming language research from here on out is wasted energy? That simplicity is all that we can ever hope for, and correctness and consistency just aren’t worth working on? Are we forever stuck with 30+ year old ideas and don’t even teach that anything else is possible?

Share this: Email

Reddit

Facebook

Print

Twitter

LinkedIn

More

Pinterest

Tumblr



Like this: Like Loading... Related

Entry filed under: Uncategorized. Tags: C, Lisp, Smalltalk.