[speed_spread]

Rust's "lifetime stuff" really is overemphasized. You can write years of totally ok Rust code without ever having to handle a single explicit lifetime. They're there, and one should have a general picture of how they work, but unless you're doing high perf / library stuff, they can generally be sidestepped.

I believe there should be a Rust manual that shows the easy way in, using Rc/RefCell before reaching for plain references. So many people get the idea that if you're not using the hardcore smallest construct to extract that very littlest bit of performance, you're "doing Rust wrong". The overall idea of Rust is that of safe code and although the compiler and language semantics obviously play a major part in it, the standard lib is actually very nice too and helps a lot to get away from the harsh realities of bare system programming.

[tialaramex]

You're benefiting from elision. Modern Rust lets you omit mention of a lifetime when there's only one plausible choice. So, often today you can write Rust that doesn't mention lifetimes but they're implied.

But it wasn't always like that. For a while Rust would insist you spell out that OK, this function parameter has some lifetime 't and the function result also has a lifetime 't. Now, Rust says well, the result needs a lifetime, and your function takes one parameter which also has a lifetime you didn't specify, so, the plausible explanation is that they're just the same lifetime, let's assume that's what you wanted and only complain if that won't compile.