If you could make any changes to D, what would they look like?

[Patrick Schluter]

On Friday, 29 October 2021 at 21:56:10 UTC, Adam Ruppe wrote:
> On Friday, 29 October 2021 at 21:16:49 UTC, H. S. Teoh wrote:
>> Long story short, pureFree makes no sense
>
> What about:
>
> void foo() pure {
>    int* a = malloc(5);
>    scope(exit) free(a);
> }
foo is pure, but malloc and free aren't individually. If the 
declaration of the purity of foo is curtailed because malloc and 
free have to be marked as pure, then it is a failure of the 
language. In fact there should be an equivalent of @trusted for 
purity, telling the compiler "trust me, I know that that 
combination of impure functions is on a whole pure". Marking 
malloc/free as pure doesn't cut it as these functions cannot, by 
definition, be pure individually.

But I start to understand where this abomination of purity comes 
from. Transitivity. I suspect that applying transitivity 
unthinkingly is not such a good idea as can be seen also with 
const (immutable is transitive as it describes a property of the 
data, const is not as it is a property of the means to access the 
data, not the data itself).



>
>
> How is that any different than
>
> void foo() pure {
>    int[5] a;
> }
>
> ?
>
> I expect that's how it is actually used. (Perhaps it would be 
> better encapsulated in a function along the lines of:
>
> void foo() pure {
>     workWithMemory((int* a) {
>
>     }, 5);
> }
>
>
> And then the malloc/free could be wrapped up a bit better)