Rust gives me hope for the future


In all of the recent political turmoil in the U.S. it's easy to get a bit down and depressed about the future. For me, a pick-me-up came from a rather surprising source... a programming language.

Now, anyone reading this post is probably enough of a computer nerd that computers are not a source of hope for the future... they are a source of the exact opposite. No computer expert can look at a programming language and not get depressed at every flaw it has. Just google "Javascript flaws" and you'll find diatribe after diatribe. C's flaws have been elevated to interview questions, I myself used to ask "what are the semantics of x++"... which would take literally 15 minutes to answer correctly. Ask a type theorist about Java's flawed generics and you'll get an hour lecture on how the designers confused top a bottom, contravariance, and why sub-typing of objects (much less generics) is a horrible idea. Alternatively, while Haskell appears to get few things *wrong* you need a PhD in category theory to understand it and like most languages that aren't fundamentally broken internally it gets relegated to the category of "useless toy".

Enter Rust

From the rust website
"Rust is a systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety."
Sounds like what they claimed about Java doesn't it? Well, it is, but rust actually lives up to it. Rust is aiming to be a direct competitor to C/C++. Remember that C was originally an "easier portable assembly code". As software engineers we tend to think of it as being nearly abstraction free, but actually what it has are a lot of nearly zero cost abstractions. These days only a few experts with a lot of time on their hands can actual beat modern C compilers in writing performant assembly code. Something only worth-while for a few special edge-case uses (like matrix convolutions). Rust takes this idea, but combine it with everything computer scientists, and type theorists in particular, have discovered about type theory since the invention of C.

The end result is the first language I've ever seen that doesn't suck. As I read through the Rust book I kept being struck by how intuitive the language is. Now, I should mention that I am a little bit biased, a few of my friends, mostly with similar backgrounds, were fairly deeply involved in it's development. This means the designers have similar biases to mine.

Rust has got to be the most complex language I've ever learned... but then again, I didn't just pick up and start trying to code in C++14 without knowing C and older C++ standards first. The difference is that C++14 and similar languages don't just require learning all the keywords and what they mean, they require learning which code is defined and undefined. Ever try to actually write code that is fully defined? Sequence points are just the start of it. Just check out out the differences between char and int8_t... char (called that because it's frequently used for characters... though does completely the wrong thing with utf8 without serious effort) is assumed to alias something else, and int8_t does not. If any part of that sounded like babble... congratulations, you don't really know C++.

The reality? no-one really knows C++. It's simply too complicated a language with too many corner cases. Corollary? There is no real world software written in C++ that actually conforms to the standard. Conclusion: No real world software written in C++ is even well defined, much less *correct* by any reasonable definition besides "eh... seems to work... today... on this computer and compiler".

With rust on the other hand, while the pointer types might be a little confusing at first, the keyword definitions are all there is to learn. If your code compiles (without unsafe), the behavior is defined, and that's the end of it. No aliasing rules, no sequence points, etc. Almost all of your code can be written like this. For those rare little corners where you really need to punch through that safety, unsafe is there for you.  C's semantics got screwed up by optimizing compilers, the problem was that it's definitions are a little *too* low-level (original defined by direct translation to Vax assembly instructions), so optimizing required violating the original rules and we got the crazy dance we have today. Something like SML is so divorced from the system that punching down to understand the machine-level is almost nonsense. Rust is right in between where optomizers can optomize, but the machine layout is defined enough that when you use unsafe, it just works.

It's strange to say, but as I watched the news scroll past and read the Rust book... I felt flushed with hope. Not only can software theoretically not suck, but people actually put together a tool to help us do it. A tool that itself is software that doesn't suck. Maybe, just maybe, humans can actually do this technology thing and make it all work.