[dmurray]

> And the clumsy Arc<Mutex<Something<TheOtherThing>>> makes users feel bad about using runtime cost paid types

Yeah, this would look worse than any of the "complicated syntax" examples in the blog post.

A language should be designed so that the typical case is the easiest to read and write. Syntax for the most common abstractions. Rust forces you to be explicit if you want to do an Arc<Mutex<Box>>>, but lets you inherit lifetimes almost seamlessly. That means it's not idiomatic to do the first, and it is to do the second.

Languages with a lot of historical baggage don't follow this pattern: if you want to write idiomatic modern C++ it's going to be uglier and more verbose than you see in K&R. But in Rust's case it's clear what the designers encourage you to do.

[_answ]

Simple != idiomatic. It's perfectly idiomatic to `Arc<Mutex<Box>>` in Rust, and it is more complex because it deals with more concerns than a simple reference, namely being thread-safe. Sometimes you need that, sometimes not, but you have to be explicit about it.

[steveklabnik]

There’s no reason to have a Box<T> there, because Arc already boxes.

[cozzyd]

Not sure why you'd compare modern C++ to K&R which is a C book. Modern C is in fact less ugly than ancient C due to sugar like compound literals.