Re: Papers saying Ada as an overly complex language and hard to implement

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

Yongxiang Gao says

<<For a beginner, "rich" comes with "complex to use".>>

Speaking from the point of view of having taught Ada to beginners, I 
regard this unsubstantiated claim as nonsense. You do not teach beginners
all the features in a language on day one, and I have found that the
fact that Ada is feature rich has no significant impact on the process
of teaching Ada to beginners.

<<Who tells you "Ada is no more difficult than any of these other languages"?
 Do you know the stories of Ada implementation in the early 80's?>>

To which one might reply, do you know who I am??? :-)

Yes, I am very aware of the Ada implementations in the early 80's. First,
I lead the team that did the first validated implementation, and second,
I worked extensively for Alsys, one of the companies doing these
implementations.

Yes, it is true that writing an Ada compiler is not an easy task, but
neither is writing a compiler for any of the other modern large languages.
PL/1 was hurt badly early on by the difficulty of writing good compilers.
C++ compilers have taken a long time to begin to get reasonably reliable,
and almost none are fully ISO-compliant yet. The difficulty of implementing
Fortran-90 is great enough that it is still nowhere near universal, despite
the date. OO COBOL is *quite* hard to implement (I was involved deeply in
a COBOL implementation, and in some of the discussions leading up to
OO COBOL). Algol-68 was badly hurt by the amount of effort required for
good implementations.

And yet we see isolated examples in each case where good compilers have
appeared on a reasonable time scale (DEC Ada reached a good level of
maturity early on, as has, for that matter GNAT, which is only six years
old at this stage). The CDC implementation of Algol-68 was complete
and excellent. The GE implementation of PL/1 on Multics was highly
effective, and the IBM F90 is coming along nicely.

Remember the issue here is whether Ada is *more* difficult than other
languages. There is no technical reason to think the answer is yes, and
there is no experience which would indicate that the answer is yes. All
we have is your unsubstantiated belief that this is the case, and the
assumption that therefore there must be papers supporting this
belief. I know of no such papers.

As for being constructive, I am trying to be constructive, but you are
asking for papers verifying assumptions that you are making that are
simply not valid!