What? You need to make a function to make a loop? That can't be right???

Ah no, there is a misunderstanding. You can write C-loops, of course, they just could involve more work under the hood because in order to enforce memory safety, there needs to be some form of bounds checking that does not happen in C. Caveat: I don't know whether that's always true, and what the subtleties are. Maybe I'm wrong about that even, but what is true is that what I am about to say, you will encounter in Rust codebases.

By function composition I meant in the mathematical sense. So, this example explains the gist of it. You may need to throw in a lambda function in there to actually do the job, yeah. I don't know what the compiler actually reduces that to though.

It's just the more functional approach that you can also see with Haskell for example. I find it harder to parse, but that may be lack of training rather than intrinsic difficult.

EDIT: pasted the wrong link to something totally irrelevant, fixed now