Re: Free Optimizing Ada Compiler

[pattis@june.cs.washington.edu (Richard Pattis)]

In article <9105091625.AA11977@enuxha.eas.asu.edu> koehnema@enuxha.eas.asu.edu (Harry Koehnemann) writes:
>It's not just that, it's also resources.  It been discussed here to put
>Ada as the beginning language, but what are the consequences of doing
>so.  A university can get a site license for pretty cheap.  However,
>compile 15 C programs concurrently and then 15 Ada versions for
>equivalent programs and you'll see the magnitude of the problem.
>
>Harry Koehnemann
>koehnema@enuxha.eas.asu.edu

Actually, in my expericien this is not much of a problem. For a sufficiently
fast machine, a large number of beginning students can easily share it, since
at any given time most are editing their programs (or typing commands to the
debugger, or typing input/reading output, or doing some other non CPU-
intensive operation).  I teach a beginning programming course in Ada, with
about 150 students, concurrently with an intermediate Ada course, with about
70.  We share a machine with other classes: it has between 50-250 users
logged on at any given time. Throughout the quarter I randomly log on and
compile complex Ada program.  I find that when I compare the CPU and Wall-
clock times, I get between 1/2 to 1/3  of the CPU time for my compilations.

I don't have any information comparing Ada vs C based on the total number of
compiles it takes to get a program correct. While it is easy to measure the
absolute speed of a C and Ada compiler, the more important quantity to measure
is how long it takes the student to get a working program (summing all the
compile times he/she uses).

In fact, I will even go to the extreme here and say that it is often BETTER in
beginning classes to not have instantaneous compilation. When compilation is
TOO FAST, it can seduce students into repeatedly reusing the compiler in place
of actually thinking about what they are doing. I often see reasonably written
programs turned into garbage by students incrementally changing them without
thinking about what they are doing. I am not saying all beginning students
succumb to this temptation, but it is my experience that many do.

Rich Pattis


-- 
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  Richard E. Pattis			"Programming languages are like
  Department of Computer Science	 pizzas - they come in only "too"
    and Engineering			 sizes: too big and too small."