Re: Ada for Boeing 777

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

Interesting quote"

>   "What we have learned so far about the use of Ada on the 777 is a mixed
>    message. ... We found no correlation between the languages used and
>    the number of problems found on the system.  We found instances where
>    Ada was used effectively, and the developers felt it substantially
>    reduced software integration problems.  In other cases, development
>    was hampered by problems with compilers and other support tools....
>
>    The richness and complexity of the language helped knowledgeable users
>    with mature tools achieve modest productivity gains.  However, the
>    complexity of the language caused headaches for other users who had
>    to work through compiler problems. ..."

What we have here is two notes that the language itself was helpful, and
two notes that tools were a problem. Note that even the negative mention
of the complexity of the language is apparently directly related to the
assumption that this complexity is what is causing "compiler problems".

As is often the case, people do not stop to carefully distinguish the
language from the implementation, and to be fair, why should they? After
all they have to use a compiler to use the language. 

It is certainly the case that a disadvantage of complex languages is that
it is harder work to get reliable tools. This applies independent of the
particular language used (for example, C++ compilers are typically much
buggier than C compilers). 

One problem with the 777 was that, at least as I understand things, a
decision was made to use Ada, and then to use processors for which mature
Ada compilers did not exist. This is of course a recipe for aggravating
the difficulties caused by compiler problems.

Clearly a critical issue for the success of Ada 95 is to bring Ada 95
compilers and tools to the best possible level of maturity as quickly
as possible -- so I think I had better get back to work on GNAT :-)