Awesome question, you're getting at the good stuff.
Short answer: Valen would have something similar to Fn and FnMut (but phrased in terms of effects rather than Fn vs FnMut). In other words, we would be able to express "a closure that does not modify anything it captures", or rather, "a closure that has no mut effects".
That closure, because it doesn't modify anything it captures, would be safe to share among multiple threads in a structured-concurrency-like / std::thread::scope-ish way.
The key here is that one _can_ express immutable references in Valen; an immutable reference is a reference that the containing function doesn't express a `mut` effect for. And once we have immutable references, we get all of the nice concurrency benefits that Rust trailblazed.
I'd also like to make a way to do the above without a function call, perhaps using something like the `parallel` keyword I described in [0].
A no-access reference is an interesting idea. That could be a more powerful way to express may_dangle. In Valen, I hope to have an "opaque" group to express something like that.
I don't know whether it's a good idea, but in Valen I'm trying to decouple access capabilities away from the reference types as much as possible. We'll see if that bet pays off.
[0] https://verdagon.dev/blog/seamless-fearless-structured-concu...
Short answer: Valen would have something similar to Fn and FnMut (but phrased in terms of effects rather than Fn vs FnMut). In other words, we would be able to express "a closure that does not modify anything it captures", or rather, "a closure that has no mut effects".
That closure, because it doesn't modify anything it captures, would be safe to share among multiple threads in a structured-concurrency-like / std::thread::scope-ish way.
The key here is that one _can_ express immutable references in Valen; an immutable reference is a reference that the containing function doesn't express a `mut` effect for. And once we have immutable references, we get all of the nice concurrency benefits that Rust trailblazed.
I'd also like to make a way to do the above without a function call, perhaps using something like the `parallel` keyword I described in [0].
A no-access reference is an interesting idea. That could be a more powerful way to express may_dangle. In Valen, I hope to have an "opaque" group to express something like that.
I don't know whether it's a good idea, but in Valen I'm trying to decouple access capabilities away from the reference types as much as possible. We'll see if that bet pays off.
[0] https://verdagon.dev/blog/seamless-fearless-structured-concu...