> I.e. Rust right now is excellent at certain things ("linear things"), and okay at non-linear things. But could it be made to be really good for the latter too

> I.e. Rust right now is excellent at certain things ("linear things"), and okay at non-linear things. But could it be made to be really good for the latter too? Having written programs in Rust and Haskell, which are in this regard quite similar, I think that you can express most of your application in a "linear" fashion and only have a bit of "non-linear" things at the top. For example if you have to handle some "non-linear" things like events from the system or a gui library, then you might have - in Rust terminology - a 'RefCell<Rc<AppState>>' to be able to have shared mutable access to the application state. At the top of the event handler you would transform the 'RefCell<Rc<AppState>>' into a '&mut AppState', which is the switch from the "non-linear world" to the "linear world" and involves a runtime check that there's only one mutable reference. All the following code of the handler can then be verified at compile time. This also makes the reasoning about the application easier, because you might even reduce the mutation of your application state to the switching area. So most of the event handling could be a pure transformation of the application state.