Re: Everything You Know Is Wrong

["G.B." <bauhaus@futureapps.invalid>]

On 29.12.15 18:36, Dmitry A. Kazakov wrote:
> On 2015-12-29 17:57, G.B. wrote:
>
>> The point is that, since order does not matter among these parallel
>> computations, and since parallel loops are not just fantasy,
>> the possibility of postponement follows from parallel loops.
>
> Ada does not have parallel loops.

Ada is about to have parallel loops. Ada compilers already produce
code for parallel execution of loop bodies on today's processors.


>> Consider F1 and F2 from a Pure package, X a variable of type T
>> and T without progenitors:
>>
>>     declare
>>        A : T := F1 (1,2,3);
>>        B : T := F2 (X);
>>     begin
>>        G (A, B);
>>     end;
>>
>> Is it impossible for a compiler to see that the initializing parts of
>> the declarations of A and B are independent?
>
> No, because initialization of T may have side effects.

I assume you meant Yes, impossible. But,
if F1 and F2 are from a Pure package, is the compiler allowed to
ignore side effects because the programmer specified Pure? I think
that follows.

> BTW, why do you believe that the same amount of computation performed
> consecutively should require less energy or (not quite same) less
> battery drain?

Less energy at a certain point in time. Postpone calling sub if, say,
a photocell should first be given time to recharge a battery while
while regular operation continues, then call sub.