On Sunday, 7 October 2018 at 02:01:17 UTC, Manu wrote:
... but I'm really struggling to express it in terms of the type system...
I'm pretty sure no simple attribute system is any more useful than current const\shared idiom. I am yet to see a language with semantics that actually help with concurrency issues (serializability, lock domains, lock ordering, deadlock prevention\detection, consistency, write scew and hundreds of other problems already known in the domain) on mutable state. SQL didn't solve it, I still always have to grab pen and paper and brute-force simulate concurrent access to my data in order to have any degree of prior knowledge about safety, and unfortunately this problem does not look like an easy one to crack for language designers.
This is why I mainly ignore shared as a feature completely unless I'm forced to. A simple indication (type system attribute) of the fact that data is shared is useless for my recent projects just adds unneeded casts and lines of code without solving any problems.
