Re: Array mappings

[mfeldman@seas.gwu.edu (Michael Feldman)]

In article <3cv7t2$no2@gnat.cs.nyu.edu>, Robert Dewar <dewar@cs.nyu.edu> wrote:
>Mike, you sure have posted lots of messages on the Fortran array issue. My
>own feeling is that this is a nice feature, but not particularly critical.

Well, clearly we are all entitled to our own feelings. :-)

>Having to reorder array subscripts is not exactly the biggest barrier to
>the use of Ada arrays in Fortran programs! 

Which barriers are bigger?

>You ask if vendors explicitly
>ran around trying to "dig up" this market. I doubt it. Instead they probably
>assumed that this was not a major issue, because no customers bought it up.

This may well be true. The array issue is really only subsidiary to the
bigger one of whether it is possible to attract more of the "traditional"
engineering/science community to Ada. I'm still waiting (I may wait a
long time...:-)) to hear someone who was there say "the engineering
market was thoroughly studied and we concluded that it was hopeless."

At the risk of pre-judging, I think the Ada vendors were - during the
years when it might have made a difference - so fixated on the DoD
"embedded systems" customers that it never occurred to them to do
serious study of all those non-realtime people whose computers are
used to _compute_ - in DoD, DoE, and elsewhere. Judging from the
activity around Fortran 90, that is _not_ a negligible market.

>As for it being a possibly lucrative market, I VERY much doubt it. THere
>were much more important targets of opportunity than this one.

Such as?

>It is true that it would not have been very hard to implement, which just
>goes to show the estimate of value placed on this feature by vendors, and
>personally I think that this was a reasonable estimate.

I don't know. With absolutely no data to go on, and no vendors coming
forward to supply any, I can only speculate. The fact remains that
Ada is not exactly a big player in engineering.

>Ada 9X requires this support. Whether that requirement is justified
>remains to be seen. That will really show whether Mike is right. If we
>see a huge army of Fortran programmers suddenly saying "great, now that
>I can write my subscripts the "right" way round in Ada 95, I will switch
>to using Ada", then we will know that Mike was rigt, and that Ada vendors
>missed an important opportunity.

Well, given that F90 provides nearly all the language maturity that
an engineer would need, I see it as rather unlikely at this point.
I don;t think the array subscript issue is the only adoption barrier,
but the aggregate of this and other issues (the lack of a quasi-standard
math library, for example) contributed, I'm sure. Actually, I think that
in this as in other domains where Ada has poor penetration, the barriers
were mostly nontechnical. But certainly fixing the obvious technical holes
might have taken some excuses away.

>Note: Many Fortran programmers are moving to C, C doesn't have any help
>for Fortran array ordering, and I never heard of this being an adoption
>barrier.

Why do you suppose they are moving to C? Apparently C is giving them 
something Fortran couldn't. Or is it just the same "mob psychology"?
Don't you think it's worth an attempt to get Ada into that game?

Mike Feldman