The programming language is the single most important choice a teacher can make, since it is the technology that students encounter the most. Unfortunately, languages like Pascal and C++---and their programming environments---are virtually unchanged since the early 1970's, so they are unable to capitalize on over two decades of computer science research which can have a direct positive impact on the quality of education.

For these reasons, we prefer the programming language Scheme, and the programming environment DrScheme. DrScheme is described in more detail later in these slides.

Scheme has many salient features:

• It is far removed from the details of the underlying hardware and operating system. In languages like C++, students must constantly worry about details of the architecture their program is running on; often, these low-level details can produce confusing and even inexplicable results. These problems do not occur in Scheme.
• Students spend very little time on debugging. This is in direct contrast to the approach with traditional languages. This is because, in languages like C++, many errors can only be understood by examining the innards of the system. The likelihood of this is severely compounded when students try to use advanced data structures (which is why teachers often prefer to avoid them). In Scheme, debugging in this traditional sense does not even exist. Students instead use advanced tools like program steppers to understand the behavior of their programs.
• In Scheme, even the smallest expression can be treated like a complete program, ie, it can be evaluated or stepped through. Thus students can experiment with small fragments of code and make sure the fragments work correctly before using them to build larger programs.
• DrScheme is an interactive environment. Students can enter expressions and immediately see the result of evaluating them. There is no lengthy compilation phase, and students are shielded from unnecessary details like linking. Since the environment offers rapid feedback, students are encouraged to explore their ideas; since it is gentle, they are not punished for doing so.

Conventional languages like C++ differ in all these respects. They create artificial obstacles unrelated to the essence of programming. Since students must overcome these obstacles before they can feel comfortable programming, students often develop the incorrect (but justified) opinion that programming is a mundane and boring activity. In particular, students who are uninterested in the arcana of computers, or who seek more creative challenges, are turned off of computer science entirely.

See a concrete example of how C stacks up against Scheme.

Last modified at 20:34:32 CST on Saturday, November 22, 1997