I would prefer to use std.rt.io, instead of use std::rt::io. For the later, I need to press the keyboard for 3 * 2 times more. Java and C# use . to separate packages and access methods/fields too. IMO, . is 4 times better than ::.
std::task::spawn(...) -> std.task.spawn(...)
We don't really need to write so many dots in Rust source code.