Isolated by example

[via Digitalmars-d]

On Friday, 2 May 2014 at 18:32:13 UTC, Dylan Knutson wrote:
> Correct me if I'm wrong here, but this seems really similar to 
> how Rust does owned pointers and move semantics. Or is there a 
> large conceptual difference between the two that I'm missing?
>

Yes, there are some parallels, although there's no "merging of 
islands" in Rust, AFAIK.

> I believe that the issues that people are bringing up with bad 
> interaction with UFCS, and losing isolated data after passing 
> it to a function, are managed in Rust with the notion of a 
> borrowed pointers. Perhaps something analogous to this could 
> accompany the `isolated` idea?

This will definitely need more thought. I also don't think that 
UFCS is special; methods should probably be just treated like 
free functions with a hidden parameter, just as they are for pure.

Purity might be one part of the solution here: pure functions can 
for example take isolated arguments without consuming them, iff 
their parameters and the isolated variable have "incompatible" 
types in that it mustn't be possible to store a reference to one 
in the other. (The same is true for scoped variables: they cannot 
escape their scope, even if the pure function's params are not 
marked as scope.)

Another option are scope/in parameters.

All of this purity, isolated, scope, uniqueness business is 
closely intertwined... there just needs to be an elegant way to 
make it all fit together.