Re: Inheritance versus Generics

[dewar@merv.cs.nyu.edu (Robert Dewar)]

<<> Applying the Dewar principle would have meant that none of that
> criticism was meaningful, since none of the critics had any
> extensive practice in the languages being discussed (especially
>>

Let me make a distinction here. Obviously one can discuss specific technical
aspects of a language without having written piles of code. For example,
given my experience, I would say it is a mistake to design a language
without recursion in its basic procedure invocation structure, and I would
consider that a legitimate specific criticism of COBOL, even by someone
who had not written piles of code in COBOL.

What is not legitimate is to make overall judgments of usability in general
or in specific domains. In other words, if you now carry that worry about
recursion in COBOL to make a statement that COBOL is not useful for
applicatoins in xxx domain, without having experience in how large COBOL
programs are written, then you are almost certainly speaking nonsense.

I was always amazed by how many people who did not know COBOL at all 
were surprised to find out that Realia COBOL was written 100% in COBOL.
They simply assumed that this would be tricky, and that we must have had
great difficulty doing this. Complete nonsense of course -- I would far
rather write a compiler in COBOL than in C (and that is based on having
done both!) Indeed, let's take the recursion example. One might assume
that lack of recursion in a language would be a nuiscance, especially
when compiling a language like COBOL with a heavily recursive syntax.

In fact in the kind of domain we were working in, with a limited memory,
it is always a bad idea to use recursion in a compiler, since it introduces
complexity limits into programs that are induced by the maximum memory
available (Realia COBOL is one of the very few compilers I know of that
has aboslutely NO limits of any kind other than available disk space, and
in an environment with only 200K or so of available memory (no virtual
memory around) can compile programs that are millions of lines long.