IIRC, Rust's idea of controlled mutability originally came directly from the Erlang idea of immutable messages between tasks. Certainly, in the classic "Project

IIRC, Rust's idea of controlled mutability originally came directly from the Erlang idea of immutable messages between tasks. Certainly, in the classic "Project Servo" presentation [0], we can see that "no shared mutable state" refers specifically to sharing between different tasks. I think it was pretty early on in the project that the idea evolved into the fine-grained aliasing rules. Meanwhile, the lightweight tasks stuck around until soon before 1.0 [1], when they were abandoned in the standard library, to be later reintroduced by the async runtimes. [0] http://venge.net/graydon/talks/intro-talk-2.pdf http://venge.net/graydon/talks/intro-talk-2.pdf [1] https://rust-lang.github.io/rfcs/0230-remove-runtime.html https://rust-lang.github.io/rfcs/0230-remove-runtime.html