On Scheme

Thoughts on Scheme and teaching Scheme

Archive for April 25th, 2006

Theory and Application

Posted by Peter on April 25, 2006

No one seems to like the computer science curriculum offered at universities. The complaints I hear most often are that there isn’t enough theory, and that there isn’t enough practical application of concepts. Initially I thought that these goals were mutually exclusive, and that people complained simply because they were taking the wrong kind of courses. However, when you look at what actually is taught, you come to realize that some courses manage to leave out both theory and application when they could easily have had both. Before I show how both theory and practice can work together I probably need to defend the importance of each to computer scientists.

Let’s talk about theory first. When I think of theory I think immediately of math, and I think this connection tends to scare away some students. The theory side of computer science, ideally, deals with computation as an abstract process, which can be studied in order to prove, often with math, what is the best solution for a given problem. For example, theory teaches how to analyze algorithms under different conditions for speed and space efficiency. The theory side also encompasses topics such as how to mathematically model networks, lambda calculus, information theory, ect. In all honesty learning theory isn’t much fun, but it is necessary. The most important consequence of theory is that it encourages new “practical” advancements. For example the theory of lambda calculus gave birth (partly) to Lisp. Knowing more about information theory will help you design better network transport protocols and compression schemes. Advancements can be made without a theoretical background, but they tend to be made slowly with many revisions. Ideally theory can tell you directly what the best solution to a problem is, allowing you to implement that best solution in the beginning, not after 15 beta versions.

Practical knowledge however is also important. Obviously without actual programming experience you can’t put any of your wonderful theoretical knowledge to use. Programming and other practical applications also give insights into the capabilities of current software and hardware. Often the physical limits of the computer will determine what theories can be made into a real system, and you won’t be familiar with these capabilities unless you deal with them regularly. Finally, the desire to actually implement something is an excellent vehicle for learning more about computer science in general. For example I first learned how networks functioned before I even went to college because I was trying to create a chat program (in order to cheat on the computer science exams, but that is another story).

When I look over the classes offered at my affiliated university I notice some gaping holes, in both the applied and theoretical curriculums. The most noticeable missing applied class is one on debugging, which has always struck me as odd. Programmers can waste a lot of time trying to find bugs, I know I do, but for some reason students aren’t taught how to debug and are expected to learn on their own. As a result students new to programming often spend more time trying to find errors in their programs than they do writing them. In the theoretical side of the curriculum a class on information theory is clearly missing. Information theory has its fingers in every aspect of computer science, because from one point of view all any program does is manipulate information. Once again universities seem reluctant to actually teach students this material, expecting students to pick it up on their own.

Ideally application and theory should go hand in hand in the classroom. For example if you were teaching a class on mathematical approach to networks, with regards to speed, connectivity, ect it would be reasonable to have the students implement some of the best models that result from the mathematical study. Likewise purely practical classes, say a class on XML, could be enriched by applying that practical knowledge to an abstract domain, for example implementing abstract syntax trees in XML. Instead what we have are mediocre classes that do neither. For example take a look at any text book on operating systems. Inside you will find plenty of general information, but you will not find any code, not even pseudo-code. Nor will you find any theoretical underpinnings for why operating systems work the way they do. Instead these books stick to giving outlines on topics such as “what is a file system?”. Classes on networking, hardware, artificial intelligence, and many others, all follow this pattern, with students being exposed to little theory and less concrete application of the concepts.

Of course if you are a self motivated computer science student this won’t be too much of a problem for you. Now that you know what kinds of things your education is lacking it is easy enough to learn them from the internet (for the most part). Of course if you aren’t a self motivated student then this isn’t much help, but then again if you aren’t a self motivated student why are you in computer science?

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Miscellaneous Day

Posted by Peter on April 25, 2006

I have a couple points I want to bring up today, none of which are lengthy enough to warrant their own post.

Point 1: Debugging multi-threaded applications sucks (in C++ at least). As you may know I have been working on asynchronous garbage collection. I have been debugging some of the basic parts in the last few days, and am constantly being bit by multi-threading. Some of it admittedly is my own fault, for example I forgot how to write a blocking queue properly. Unfortunately any mistakes, no matter how small, turn into major bug hunting excursions, because they are affected by timing in the most unpredictable ways, making it is hard to repeat them. For example putting in print statements to find out where a bug was caused the bug to disappear. Secondly I can’t step through the threaded code with the debugger, meaning that I have to rely on print statements. At the moment I think I have the bugs on the defensive, but if any more pop up I am going to have to implement an asynchronous logging routine.

Point 2: My bile got posted to reddit; i.e. last time’s post “In Defense of Change”. Admittedly it is nice to have so many people hear your opinions, but at the same time it has a downside, since many of them will come to the conclusion that I am full of hate after reading it and will never visit the blog again.

p.s. If you want to take a look at the garbage collector I wouldn’t be opposed to sending the code out on request, but since it is not really ready for public consumption it isn’t on Sourceforge yet.

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