SIGCSE 2022 - APCS-A Language strengths and weaknesses
Last time we talked about the intent of APCS-A and without deciding on that we can't really chose a language. Still, we can talk about strengths and weaknesses of languages. Let's do that by taking a walk down history.
APCS started in Pascal. Back then it was a one year course that included CS1 (programming) and CS2 (data structures). Later they offered two exams A (programming) and AB (programming plus data structures). The AB exam was last administered in May 2009. In it's last year, only 3,881 students took the AB exam - about 10% of those students were from Stuy.
The exam started in Pascal but switched to C++ in 1999. Why switch? I can't say for sure. I was a young teacher back then. Under 10 years in and wasn't involved in the greater AP scene. Pascal was a nice learning language but it had a number of deficiencies. Pascal was pretty straight forward, encouraged structured programming, required memory management which I say as a plus since it allowed one to study it and overall was a strong learning language. On the other hand, programs were limited to a single file, there was no standard for graphics or I think even file access, and it couldn't do OOP which was becoming all the rage. It also was rarely used in industry even though I did have a nice job offer back then from Brown Brothers Harriman & Co. working in Turbo Pascal.
C++ was a hot language, it supported OOP as well as multiple files. It had much greater complexity but I guess that wasn't a deal breaker for the College Board. I also have no idea if the conversation was switching from Pascal to C++ or if it was switching from Pascal to something else and then C++ was chosen.
In 2004 the exam moved to Java. Again, something gained something lost.
Java was the new hotness so no problem there. What about other changes? Java was much simpler. C++ had many ways to do things while Java nudged you into the Java way. Java also forced Object Oriented Programming which, at the time, I guess people felt was a good thing. C++ was more multi-modal and at the time, heck even today, was taught more like C with objects. Java also had a standard way to do I/O and graphics which, I guess was also a plus.
What about the downside?
Personally, I found the forced OOP to be a problem Even though the language forced all objects all the time, the nature of problems attacked in a CS1 don't necessarily lend themselves towards Object Oriented solutions. This made OOP forced and this is a problem.
Java also required a lot of "magic:" - ignore the public static void main behind the curtain. You'll understand it later.
The big loss to me and others pointed to this as a gain was that Java took out memory management. I liked that you still had to allocate memory using new to create things like nodes for trees and linked lists but you didn't have to manage them yourself.
True, this is generally a good thing but the problem was that APCS-A/B was a class, not the real world. If you were going to take out memory management from CS1/CS2 in APCS-A/B then it had to go back in somewhere or kids would never get it. This is where looking at a course and not the full sequence can be a problem. If you take something important out of APCS and then it's not in the college classes later on you've taken it out of the students overall preparation.
Based on talking to my tech friends hiring after the switch, this was a real problem.
In any event, the class chugged along, dropping the B part up through today.
So, why consider Python?
Python goes back to multi-modal and takes away the magic. Hello World is just one line. No classes necessary. Python is also, by most measures simpler. Python also has tons of libraries. You can use Flask to build a web server, NLTK to explore language, Pygame for games and on and on. Python is also used by many other fields besides direct CS.
But there's always a cost.
Python's object model is, to put it kindly, ugly and ackward. Not as bad a Perl but having to use self and no real private kind of kills it from a teaching point of view. The libraries and use in other fields are also less important if the intent is to mirror college CS1 content as opposed to rolling a new non major, more general course.
Another cost is the use of lists rather than arrays. Lists give much more power much more quickly but at the cost of teaching array style indexed data structures. This isn't a cost for everyone but it's something to consider. Related to this is that Python doesn't really have a counting loop. It has a while and a for each but not a counting for. This may or may not be an issue depending on how you feel about traversing data.
The potential big cost comes down to typing. Sure, writing
int a is
a pain in statically typed Java vs Python's dynamic typing but while
dyanmic is quicker and easier and makes sense given Python's scripting
roots, static is safer and makes it easier to write larger more robust
Memory management, is of course still long gone :-(.
So, what to do?
Python is used in many fields and is a startup darling but Java is still one of the kings, along with C++ in the industrial strength and enterprise world. I have mixed feelings and might take a strong stance but not yet.
We still have to look at more aspects of this question. Specifically what about the costs of switching from one language to any other language and also does the choice of language in CS1 matter with respect to CS2.
I'll do at least one more post maybe more to address those but I think that's it for today.