RFC: scope and borrowing

[via Digitalmars-d]

On Monday, 25 August 2014 at 01:09:59 UTC, Ola Fosheim Grøstad 
wrote:
> Cool initiative!
>
> It is probably a good idea to look at what other languages with 
> linear type systems are doing:
>
> http://en.m.wikipedia.org/wiki/Substructural_type_system

The idea is mostly inspired by Rust, but it came out very 
different. Rust's borrowing rules are way more complicated. It 
also has to deal with move semantics, for example. And it 
annotates lifetimes, not owners, and thereby gets 
non-hierarchical dependencies, as far as I understand it. I 
believe this proposal is close to the best we can achieve without 
resorting to data flow analysis.

>
> My gut feeling is that borrowing in D will suffer the same 
> problems as @safe without a high level IR that is proven 
> correct. Meaning, if the IR is correct you can add new language 
> features without breaking the type system.

I'm unfortunately not familiar with the theoretical foundations 
of type systems, and formal logic. So I'm not sure what exactly 
you mean here. It seems to me the problems with @safe are with 
the way it was implemented (allow everything _except_ certain 
things that are known to be bad, instead of the opposite way: 
allow nothing at first, but lift restrictions where it's safe to 
do so), they are not conceptual.

But if you see potential problems, or know a way to avoid them, 
this is exactly the kind of thing I'd like to see discussed.