Refinement of paragraph referenced by [this issue](https://github.com/rust-lang/rust/issues/31927).
The paragraph in question had been adjusted already, but I've made some further clarifications which should help with readability and not leave the reader any `dangling pointers`.
As a Rust newbie, I found the book's explanation for why the `filter` closure gets a reference very confusing, and tried to figure out why `filter` is somehow less consumptive than `map` -- but it isn't; that's controlled by `iter`/`into_iter`. I flailed around for a while until @habnabit explained it to me, and in retrospect it is quite obvious :-)
I feel sorry for bothering you with such a literally one character changes. If it is counter productive feel free to point it out in the comments, that would be totally understandable. I could try to pack such a changes together in one PR to make them less distractive.
r? @steveklabnik
Not everyone knows this convention. We could just rename the variables in the
example, but since this notation is commonly used it's a good opportunity to
introduce it.
r? @steveklabnik
This is a minor change. Please see title. IMO this is important since this is the first instance when we talk about allocating a vector. Not saying that it is allocated on the stack here leaves room for speculation and this might put off some people (they might not even read the later sections which go into more detail about this).
Some other shufflings as well:
* Three powerpc triples for Linux have been added recently
* An armv7 linux triple was added recently
* The 64-bit Solaris triple is now mentioned in tier 3
We are currently now also building nightlies for iOS, powerpc triples, and
armv7, but there hasn't been much vetting of the triples themselves so I've left
them in tier 3 for now.
Fixes#31334
This is just a quicker fix for this issue; since I'm working on the next draft of the book, I don't want to put a huuuge amount of work into improving it here.
Updated documentation to clarify the difference between `and_then` and `map`. This also explains why we need `and_then` in addition to `map`. Please look at the diff for more information.
r? @alexcrichton
Some other shufflings as well:
* Three powerpc triples for Linux have been added recently
* An armv7 linux triple was added recently
* The 64-bit Solaris triple is now mentioned in tier 3
We are currently now also building nightlies for iOS, powerpc triples, and
armv7, but there hasn't been much vetting of the triples themselves so I've left
them in tier 3 for now.
