Would the ownership model make D lang as complicated as Rust?

[Max Haughton]

On Wednesday, 18 November 2020 at 01:38:27 UTC, Timon Gehr wrote:
> On 18.11.20 02:19, Walter Bright wrote:
>> On 11/15/2020 6:11 AM, donallen wrote:
>>> [...]
>> 
>> It's a similar approach to how D does functional programming. 
>> You can do FP in D on a totally incremental approach, function 
>> by function. And just like doing OOP in D, you can use it in 
>> parts of your program and not in other parts.
>> 
>
> This works for `pure`, but not `@live`, because it is not an 
> issue for an impure function to call a `pure` one, but if a 
> non-`@live` function calls a `@live` one, the arguments may 
> violate invariants that `@live` users want to rely on.
>
> In any case, `pure` is transitive. `@live` is not even 
> transitive, so you get the same problems the other way around.

I think in the first case it would not be unreasonable to not 
allow a @live function (in @safe code at least) to be called 
where it cannot be guaranteed to be safe even in a more 
conservative analysis that what @live ends up being.

My personal opinion is that as soon as the ownership is ready, 
@safe should imply it. Assuming it is properly specified it seems 
like a better way of doing things than having a big list of do's 
and dont's for safe code.