The history here is very interesting, Rust went through a bunch of design iteration early, and then it just kinda sat around for a long time, and then made other choices that made modifying earlier choices harder. And then we did manage to have some significant change (for the good) in Rust 2018.
Rust's users find the module system even more difficult than the borrow checker. I've tried to figure out why, and figure out how to explain it better, for years now. Never really cracked that nut. The modules chapter of TRPL is historically the least liked, even though I re-wrote it many times. I wonder if they've tried again lately, I should look into that.
> Another example is the trait object (dyn Trait), which allows the client of a trait to decide whether dynamic dispatch is necessary, instead of baking it into the specification of the type with virtual functions.
Here I'd disagree: this is separating the two features cleanly. Baking it into the type means you only get one choice. This is also how you can implement traits on foreign types so easily, which matters a lot.
Rust's users find the module system even more difficult than the borrow checker. I've tried to figure out why, and figure out how to explain it better, for years now. Never really cracked that nut. The modules chapter of TRPL is historically the least liked, even though I re-wrote it many times. I wonder if they've tried again lately, I should look into that.
> Another example is the trait object (dyn Trait), which allows the client of a trait to decide whether dynamic dispatch is necessary, instead of baking it into the specification of the type with virtual functions.
Here I'd disagree: this is separating the two features cleanly. Baking it into the type means you only get one choice. This is also how you can implement traits on foreign types so easily, which matters a lot.