nomicon/src/vec.md

# Example: Implementing Vec

To bring everything together, we're going to write `std::Vec` from scratch.
We will limit ourselves to stable Rust. In particular we won't use any
intrinsics that could make our code a little bit nicer or efficient because
intrinsics are permanently unstable. Although many intrinsics *do* become
stabilized elsewhere (`std::ptr` and `std::mem` consist of many intrinsics).

Ultimately this means our implementation may not take advantage of all
possible optimizations, though it will be by no means *naive*. We will
definitely get into the weeds over nitty-gritty details, even
when the problem doesn't *really* merit it.

You wanted advanced. We're gonna go advanced.