[Info-vax] VMS Software Q1 '23 Update

[John Reagan]

On Friday, February 3, 2023 at 9:36:57 AM UTC-5, Arne Vajhøj wrote:
> On 2/3/2023 8:58 AM, Dan Cross wrote: 
> > In article <trhi5t$13ikm$2... at dont-email.me>, 
> > Arne Vajhøj <ar... at vajhoej.dk> wrote: 
> >> On 2/2/2023 10:08 AM, Single Stage to Orbit wrote: 
> >>> On Thu, 2023-02-02 at 06:40 -0800, plugh wrote: 
> >>>>> I'm currently teaching myself Rust and have been for the past two 
> >>>>> years. It is a most interesting programming language. 
> >>>> 
> >>>> It would be interesting to make this available on the new VMS. I had 
> >>>> some notes on this, but I don't think I kept them. 
> >>> 
> >>> LLVM supports x86_64 and ELF out the box, so I imagine the truly hard 
> >>> bits wil be the bindings to OpenVMS calls and data structures. 
> >> 
> >> I suspect that there is a bit more to get a LLVM based compiler 
> >> working on VMS x86-64 than that. 
> >> 
> >>> Async 
> >>> and locking primitives will need to be implemented, that won't be easy. 
> >> 
> >> Isn't async build on top of threads? 
> > 
> > No, not necessarily. async can be used to build threads, 
> > and async executors can run in threads, but the two are 
> > in many ways duals of one another.
> It is two very different programming models. 
> 
> But the usual async await model is that it is syntactic 
> sugar that under the hood creates a task that get scheduled 
> to run in a thread pool. 
> 
> From as programming model perspective it is: 
> 
> async await - task and thread pool - raw threads 
> 
> But implementation wise it is different levels of abstraction: 
> 
> async await 
> | 
> task and thread pool 
> | 
> raw threads 
> 
> For someone developing applications in Rust then the 
> programming model is what is important. 
> 
> But for porting Rust compiler and runtime to a new OS, 
> then the implementation matters. 
> 
> My expectation would be that if the OS expose a 
> working pthreads C library then Rust could do 
> async await on that platform as all the layers 
> in between would work. 
> 
> Of course all this stuff is most useful if 
> there is support for async IO. VMS most definitely 
> support that. But depending on what Rust rely on 
> then there may be a gap between what the Rust 
> runtime expects and what VMS has. 
> 
> Bridging *nix centric IO and VMS IO can be 
> tricky. Just look at the Java IO on VMS 
> mess. 
> 
> So I am not definitely not saying that getting 
> Rust running on VMS will be easy. 
> 
> Arne
BTW, the Rust compiler is written in Rust.  You have to bootstrap it from a Linux box.

Not a show stopper (that is exactly what we did with clang), but one more piece to the
puzzle.