alt Hacker NewsThis is one of the (several?) things that make me very worried about Rust long-term. I love the language, and reach for it even when it sometimes isn't the most appropriate thing. But reading some of the made-up syntax in the "Removing Coherence" section makes my head hurt.
When I used to write Scala, I accepted the fact that I don't have a background in type/set/etc. theory, and that there were some facets of the language that I'd probably never understand, and some code that others had written that I'd probably never understand.
With a language like Rust, I feel like we're getting there. Certain GAT syntxes sometimes take some time for me to wrap my head around when I encounter them. Rust feels like it shouldn't be a language where you need to have some serious credentials to be able to understand all its features and syntax.
On the other end we have Go, which was explicitly designed to be easy to learn (and, unrelatedly, I don't like for quite a few reasons). But I was hoping that we could have a middle ground here, and that Rust could be a fully-graspable systems-level language.
Then again, for more comparison, I haven't used C++ since before they added lambdas. I wonder if C++ has some hairy concepts and syntax today on par with Rust's more difficult parts.
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> But reading some of the made-up syntax in the "Removing Coherence" section makes my head hurt.
Articles discussions new features always have difficult syntax. There have been proposals like this going on from the start.
Fortunately the language team is cognizant of the syntax and usability issues with proposals. There have been a lot of proposals that started off as very unwieldy syntax but were iterated for years until becoming more ergonomic.
> I wonder if C++ has some hairy concepts and syntax today on par with Rust's more difficult parts.
… … … … Unqualified name lookup has been challenging in C++ since even before C++11. Overload resolution rules are so painful that it took me weeks to review a patch simply because I had to back out of trying to make sense of the rules in the standard. There's several slightly different definitions of initialization. If you really want to get in the weeds, starting playing around with std::launder and std::byte and strict aliasing rules and lifetime rules, and you'll yearn for the simplicity of Rust.
C++ is the absolute most complex of any of the languages whose specifications I have read, and that's before we get into the categories of things that the standard just gives up on.
Having used Rust professionally for six years now, I share your fear. Like many of the commenters below, coherence just hasn't been a big problem for me. Maybe there are problem spaces where it's particularly painful?
How does the Rust language team weigh the benefits of solving user problems with new language features against the resulting increased complexity? When I learned Rust, I found it to be quite complex, but I also got real value from most of the complexity. But it keeps growing and I'm not always sure people working on the language consider the real cost to new and existing users when the set of "things you have to know to be competent in the language" grows.
I really wouldn't worry much. Over the last decade of rust, very few of the articles exploring new syntax have turned into anything controversial by the time they were merged (I can't even think of big rust syntax changes other than `impl T` in arguments etc). The singular example really is async/await and, having been quite worried about it / against it at the time, it was really nothing to be concerned with at all.
> I wonder if C++ has some hairy concepts and syntax today
https://tartanllama.xyz/posts/cpp-initialization-is-bonkers/
Reflection syntax (C++26 I think) has made my 30+ years-of-C++ brain melt.
It's not insane, it's just ... melt-inducing.
Rust opened the door to innovation in the low-level languages space, but as long as it is already the most theoretically advanced practical language there, it will always attract the audience that actually wants to push it further. I don't know if there is a way to satisfy both audiences.
> I wonder if C++ has some hairy concepts and syntax today on par with Rust's more difficult parts
Yes, it's called "C++".
I wonder if Google's Carbon could fill that gap?
I wonder how Zig compares here
> But reading some of the made-up syntax in the "Removing Coherence" section makes my head hurt.
It's interesting to note the discrepancy between replies to this blog here and, say, lobste.rs (which is neutral to it).
Here it's very concerned about complexity, while on lobsters it's mostly about needing this feature - yesterday.
> I wonder if C++ has some hairy concepts and syntax today
Both better and worse.
The current version of idiomatic C++ is much cleaner, more concise, and more powerful than the version of C++ you are familiar with. You don't need C-style macros anymore. The insane template metaprogramming hacks are gone. Some important things that were problematic to express in C++ (and other systems languages to be fair) are now fully defined e.g. std::launder. C++ now has expansive compile-time programming features, which is killer for high-performance systems code, and is more expressive than Rust in important ways.
The bad news is that this was all piled on top of and in addition to the famous legacy C++ mess for backward compatibility. If you are mixing and matching ancient C++ with modern C++, you are going to have a bad time. That's the worst of all worlds.
But if you are lucky enough to work with e.g. an idiomatic C++20 code base, it is a much simpler and better language than legacy C++. I've done a few major C++ version upgrades to code bases over the years; the refactored code base was always smaller, cleaner, safer, and easier to maintain than the old version.