Re: Reference-oriented language and high-integrity software

[Maciej Sobczak <no.spam@no.spam.com>]

Ludovic Brenta wrote:
> Maciej Sobczak <no.spam@no.spam.com> writes:
>> Taking into account that JB also wrote a book about SPARK, some
>> reasoning can be found there and my understanding (simplified) is that
>> reference-oriented language implies a heavy use of dynamic memory,
>> which makes it impractical/impossible to perform any static analysis
>> of memory consumption. Garbage collectors add their own factors to the
>> problem.
>>
>> Is the above a reasonable explanation? Is it the only one? What else
>> makes the reference-oriented languages inappropriate for
>> high-integrity software?
> 
> The other part of the explanation, AFAIU, is that a reference can go
> wrong, i.e. point to deallocated memory, to unallocated memory, or to
> the wrong piece of memory.

This can be rebutted on the basis that those languages ensure that 
nothing like this happens (no pointer arithmetic + garbage collector).

>  References also introduce aliasing,
> i.e. two references can point to the same item.  All these make it
> almost impossible to statically prove that no unintended side effects
> ever occur in the program

This makes sense in case of Java, but one could also argued that 
immutability of objects - a common feature in some reference-oriented 
languages - can make it less severe.

So - let's imagine a language, which is reference-oriented with all 
objects immutable. Apart from dynamic memory, is there any problem?

-- 
Maciej Sobczak : http://www.msobczak.com/
Programming    : http://www.msobczak.com/prog/