On Scheme

Thoughts on Scheme and teaching Scheme

Archive for March 26th, 2006

Java is Bad for Students

Posted by Peter on March 26, 2006

I’ll be back with more on type systems tomorrow, hopefully, but today I want to state my objections to Java being used to teach students computer science, especially in college. Joel on Software also wrote a piece on Java schools, and his conclusion was that Java was too easy for students, that it did too much for them and thus never forced them to learn the concepts. I think this is true in terms of the number of libraries built in, for example students never really need to know how to create a linked list, however in terms of the language itself I think that Java is just the opposite, it is too complex.

Not everyone begins programming at the college level knowing about variables and classes and functions, and because of this many promising students are turned away from programming. To create even a simple hello world program in Java you need to be able to import from a library, create a class, create a function in that class, and write a complicated prototype for the main function. On the other hand in C, for example, you just need to write a very simple main function and use printf. Most teachers simply tell students to simply copy the boiler plate code, which is fine, but to do anything in Java you need to use objects, so there is a lot of code students need to copy and paste. In even the simplest programs you are using System.out to print your results and to manipulate text you need Strings, both of which require the student to use objects and method calls before they are ready to. This alone adds more and more complexity that the students are just told to ignore, or to copy and paste without it being explained to them. Even using Strings can lead to confusing problems as students wonder why String s = new String() is possible but int i = new int() isn’t. Eventually some students are able to make sense of this, but for many weeks, before objects are introduced students are engaging in a copy-paste mentality for the majority of their work.

This copy-paste mentality makes the program seem much more confusing than it really is. By the time students are introduced to objects and the difference between a reference and a value most of them are thoroughly lost. Besides, how do you explain a reference to students who don’t know that data has addresses in memory, much less what a pointer is? The answer is that you just do some hand-waving, and students learn enough that they don’t make too many mistakes, and also have no idea what it really is. Because of this the bar has to be greatly lowered on introductory programming courses, and in subsequent courses, as students enter into the system without a real understanding of what the program is doing, but only with a handful of tricks that seem to make things work.

The benefits of beginning with C/C++/ect is that in these languages it is possible to write complete programs with only a very small portion of the language. Also it is possible to explain more complex features in terms of simpler ones, for example a struct can be explained in terms of an array with named slots. Also students who understand one of these languages have a much easier time understanding assembly language, and thus what the machine is actually doing when their programs run, which in turn leads to fewer bugs and faster programs. Scheme and Lisp also have the advantage that complete programs (at the REPL) can be run with only a small portion of the language. Basically all you need to do is explain define and function calls and you are ready to go. Admittedly Scheme and Lisp don’t give students an understanding of the low level operation of the computer, however they make up for this by making it easy to teach about complex algorithms, functional programming, and data structures. For example students can be taught about binary trees using only lists, without any need for complicated structures or objects.

Unfortunately Java, which is easy to learn for programmers who have already mastered the fundamentals of programming, has been adopted in the majority of colleges, probably because of the obsession with giving their students “practical” skills. Thus this generation of programmers is coming out of college barely able to code.

Symptoms of Java Education:
-Every bug is approached with the debugger or with print statements
-Programs are never optimized
-Difficulty learning new languages
-Difficulty leaning new styles of programming

Posted in Teaching Scheme | Leave a Comment »