[brigadier132]

How do you build a data race safe language without taking on the restriction of immutable data (which is imo, a much worse and bigger tradeoff than the borrow checker)?

I actually really like the borrow checker as a tradeoff, I think it makes code much easier to understand and it makes all aliasing bugs impossible. The removal of aliasing bugs is I think an undersold benefit of using rust.

[verdagon]

There are a lot of ways, but I think the most promising ones involve regions. We do this a lot manually in Rust, but a language could make this a first class concept. Some examples:

* Vale combines generational references and linear types with regions to eliminate overhead.

* Verona lets you divide memory into regions which can be backed by either arena allocation or GC. I think this is promising because for most GC regions you can completely avoid the collections.

* Cone lets you put borrow checking on top of any aliasing memory strategy, so could be something like the best of all these worlds.

* No language is doing this yet, but RC plus regions to eliminate the refcounts, then adding in value types for better cache usage, could be a real winner.

On phone so it's hard to get links, but you get the idea. The nice thing about regions is that they allow composing borrowing and shared mutability, something that the borrow checker struggles a bit with. Regions let us alias freely, and then freeze an entire area of memory all at once. Not that Rust isnt a good approach (it is!) but there are some easier techniques on the horizon IMO.