RustCamp Reminiscences

On Saturday the first, I attended RustCamp, the first conference dedicated to the newish (in development for fiveish years, but having just hit version 1.0.0 this May, with all the stability guarantees that implies under the benevolent iron fist of semantic versioning) programming language Rust!


Why RustCamp? (It's a reasonable rhetorical question with which to begin this paragraph: going to a conference has opportunity costs in time and money; things worth blogging about are occasionally worth justifying—even if no one actually asked me for a justification.) A lot of the answer can be derived from the answer to a more fundamental question, "Why Rust?" And for me, I think a lot of the answer to that has to do with being sick of being a fake programmer living in a fake world that calls itself Python.

Don't get me wrong: Python is a very nice place to live: good weather, booming labor market, located in a good school district, with most of the books you might want already on the shelves of the main library and almost all of the others a mere hold request away. It's idyllic. Almost ... too idyllic, as if the trees and swimming pools and list comprehensions and strip malls are conspiring to hide something from us, to keep us from guessing what lurks in the underworld between the lines, the gears and gremlins feeding and turning in the layers of tools built on tools built on tools that undergird our experience. True, sometimes small imperfections in the underworld manifest themselves as strange happenings that we can't explain. But mostly, we don't worry ourselves about it. Life is simple in Python. We reassure our children that that legends of demon-king Malloc are just stories. Everything is a duck; ducks can have names and can be mutable or immutable. It all just works like you would expect from common sense, at least if you grew up around here.

And it's all fake. A child's world of rounded edges and plastic safety guards. The laws of nature wouldn't permit it to exist on its own. The old legends are true; you can't just create objects without space to put them in. But space has to be allocated, managed. Those who are brave and wise enough to study the ancient lore know how even our simplest thoughts, like setting a key in a dictionary or __init__alizing an instance of a class, are really implemented in some sort of nest of pointers traversing pointers in the underworld. I don't want to stay in my hometown forever; I want to follow the heroine's path and probe the true secrets of the underworld, to wield the virtues of our ancestors and summon the strength to lift worlds. But my wording is deliberate: the virtues of the ancestors, but not necessarily their tools. Even the greatest among us are prone to mistype or misthink; the legends tell us of lives and worlds destroyed by buffers overrun, or by trying to occupy space after the counterspell to disperse it has been cast. Lately, I had been hearing rumors of a new lore, one that grants access to the underworld and its unfathomable performance, while maintaining protective wards to shield casters from most of the inherent dangers. I had already experimented with it for a few toy programs (and used it as a bad compiler target); I made pilgrimage to the camp to learn more.

Or at least, to be inspired to more. That's most of my answer to the rest of the "Why RustCamp?" question. I'm skeptical that anyone actually learns much at conferences (lectures are notoriously less efficient than text, and mere reading needs to be combined with many, many hours of hacking to produce true skill), but getting together with people, attentively listening to them yap on stage, and mingling with the crowd during breaks, provides pointers to things to read and hack on later in addition to serving certain human social needs, giving one the strength to carry on trying to better one's mastery of one's chosen profession, even through the persistent suspicion that it none of it helps, that the young programmer's vaunted "passion" is all vanity and empty signaling that will soon be destroyed by the realization that your code doesn't really change users' lives in any appreciable way, and no one cares how smart you are. (Enjoy Arby's.)

I felt lucky that the event happened to be on my side of the bay, in Berkeley, given that the trains to the city were 503ing this weekend on account of scheduled downtime for essential security patches. On the walk from Downtown Berkeley station, I stopped at one of the outposts of the rival power to buy a specialty medicinal and a scone. I usually go to the American coffee hegemon, but the rival power has this this newish specialty medicinal, an iced-coffee with one-and-a-half kinds each of cream and sweetener, that, having tried it for the first time the day before, I privately think beats anything in the hegemon's arsenal.

I made my way to the event venue and checked in, receiving a pretty badge and the obligatory swag bag containing an event-logo tee, a tee with a clever functional-programming-dragon design on the front and a sponsor logo on the back, bottled water (which is ridiculous), a Wi-Fi password (I hadn't bought my laptop), and stickers (I almost never use stickers). I am illustrating this post with a photo of the badge and dragon tee because I forgot to bring a camera to take pictures at the conference itself, and—lest the reader object that only die-hard photography fanatics have dedicated cameras nowadays—I don't have a real phone. (I'm into technology, just not necessarily consumer technology. Maybe I'll upgrade when the Ubuntu phone goes on sale in the U.S., but likely not even then.)

I was mildly surprised at the number of familiar-to-me faces in attendance (from my native subculture, or indeed more specifically from the party on Thursday, or from non-Rust programming scenes), but I guess this shouldn't be surprising on anthropic grounds. I speculated that there would be a lot of relative newbies (like me) at this event as contrasted to a conference for a more established technology—more people come to RustCamp because they want to check out the hot up-and-coming new language than because they've been doing it at their dayjob for five years. (During post-registration mingling, someone mentioned wanting something like Haskell's Maybe types, and I said, "I think we call it Option around here.")

The talks were in a big room with a bunch of circular tables (the tables were also mildly surprising to me; I guess I had been expecting rows of chairs, but no doubt it's better for laptops to not literally have to rest atop laps).

First, Aaron Turon and Niko Matsakis gave a keynote (PDF) about how far Rust has come and what remains to be done on the timescale of a year or so. They mentioned that there's a tool called Crater that tests a build of the Rust compiler against the packages on, to detect regressions with respect to how people are actually writing Rust in the wild. And the 1.0.0 API stability guarantee certainly doesn't mean there's not a lot of work left to do on the compiler. Apparently, as of now, rustc builds a big AST of your entire crate and hands that off to LLVM, which can lead to disappointingly slow compile times for large crates, but people are working on a more modular "middle intermediate representation" that will allow fast, incremental compilation at the level of individual functions. There's also work on making the borrow checker less dumb (in the matter of rejecting perfectly good code that it doesn't yet know how to prove is safe), and IDE support ("It's come to my attention that some people are not satisfied with Emacs"). In the gap after the keynote but before the first non-keynote presentation, I had a good conversation about cartoons with a fellow attendee.

Alexis Beingessner gave a really informative talk that the program called "Who Owns This Stream of Data?", but which the slides called "OMG ITERATORS". Beingessner's presentation style seems to be characterized by a kind of affectedly enthusiastic Buffy Speak that I can't quite bring myself to criticize, but only because I expect people would say similar (though not identical) things about my writing. In the toy Rust programs I've written so far, I've gotten used to calling .iter() on a vector in order to iterate over it in a for loop. This is a part of Rust's Iterator trait, implementations of which have to provide a next function that returns an Option of the type you're iterating over. (It's just like Python, except that in Python the method names have double underscores around them, for implicitly calls .__iter__() for you, and we raise StopIteration instead of returning the None alternative of an Option!) But it turns out that Rust actually had other kinds of iterators that correspond to different ways of using Rust's ownership system (where multiple things can have a read-only reference to a piece of data, but only one thing can have the ability to write to it at a time in accordance with "ownership" and "borrowing" rules that I don't really understand yet). So .iter() gives shareable immutable references, .iter_mut() gives restricted-use mutable references, and .into_iter() actually moves the data out of the collection (almost like a Python generator, which can't be reset once exhausted). And there was something about this cool trick where you iterate over indices of a vector backwards so that you can conditionally use swap_remove to take stuff out of the middle in constant time.

Matt Cox gave a talk on "Learning Systems Programming With Rust" that I had really been looking forward to. He explained memory on the stack and the heap with cute animations of unofficial Rust mascot Ferris the crab gliding around putting values into boxes. Unfortunately, there seemed to some kind of mistake where he had an outdated version of his slides?—the talk got wrapped up awkwardly, and I wish we had gotten to hear the rest of what he had in mind.

There were a few talks about some companies' experience actually using Rust in production, and somebody wrote a clone of Graphite in Rust. Somehow I don't have a whole lot to say about these.

I really liked Carol (Nichols || Goulding)'s presentation on doing code archaeology with Git, issue trackers, and mailing list archives. The topic was dear to my heart, given how much of a Git-blame–intensive workflow I have (I M-x vc-annotate constantly). During the second example, on using blame and log to track down the origin of the lifetime elision rules, I found myself wondering if she was going to mention the Git log pickaxe and whether I should try to bring it up in Q&A if she didn't. Then she did discuss it in the third example, mentioning in passing that she didn't know why it was called the pickaxe. Someone in the audience tried to argue that the -S switch resembled a pickaxe. "No, it does not look like a pickaxe," (Nichols || Goulding) replied, "I don't think you could cut down any trees with a dash capital-S."

Carl Lerche talked about his Mio library for asynchronous I/O in Rust; I also don't have a much to say about that one, except that the typography on his slides was very tastefully done.

Yehuda Katz (of Bundler and jQuery fame, amongst others) talked about how to call Rust code from C (or your favorite other language via C extensions). "Rust," he argued, "is a DSL for describing ownership concepts that you have to think about while using C or C++." He recommended that for anything more complicated than simple numerical types, you should translate Rust types to an opaque void * pointer in your C code, and put that in your language's object type if you're writing a C extension. (You can write and expose Rust functions to do useful things with it.)

Finally, Nick Cameron talked about using functionality of the compiler to write tools for Rust, like extra linters and smart code search. Listening to him actually gave me a cool project idea that has nothing to do with Rust, namely that you could write a tool using Python's ast module to count how often which variable names are used, and cross-reference it with Git blame (the AST-node objects know what line number they're from) to see if different members of your team make noticeably different variable name choices.

So that was RustCamp! It was fun, but if I want the fun to have meant anything in the end, I'll have to put more effort into learning Rust properly.

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