I think more importantly Rust has to clearly demonstrate that it really is better for projects that use C currently. I think the failure of wider adoption of D is a good case study.

> I think more importantly Rust has to clearly demonstrate that it really is better for projects that use C currently.

I halfway agree. More evidence is always welcome, but the nature of that evidence will almost always be subjective, and I'm not sure a lot of language adherents even care all that much when the evidence is objective. So more is better, but "clearly demonstrate" may be pie in the sky thinking.

> I think the failure of wider adoption of D is a good case study.

I always considered D interesting, but not worth the effort for the gains it offered. A more ergonomic C/C++ is nice, but ergonomics just steer you the right way, they're a far cry from preventing a while class of errors. A GC does offer some help in that direction, but comes with a clear continuous cost. Compiler level error prevention with zero cost abstractions comes across as something a bit more new and novel, and changes the cost/benefit analysis some. It's now a one-time up-front cost, with the possibility that the cost will lesson over time as you become more accustomed to the language.

From an outsider's perspective, Nim was actually a lot more attractive than D as a replacement for C/C++. The cost seems almost negligible since it compiles to C, which makes the benefit fairly good (if overall of less magnitude than I perceive the benefit of Rust to be).

"I halfway agree. More evidence is always welcome, but the nature of that evidence will almost always be subjective, and I'm not sure a lot of language adherents even care all that much when the evidence is objective. So more is better, but "clearly demonstrate" may be pie in the sky thinking."

One way to clearly demonstrate this in my opinion would be big projects that are implemented in Rust. I remember when Java came up there were plenty of people saying that it would totally replace C/C++ but you just had to look around to see that not much big software was written with it. Same for C#. Once we see something widely used like git, a big database, a web browser or similar written in Rust then we know Rust has arrived.

In that respect, I think Servo and Firefox is the big project. Unfortunately (or fortunately, depending on the direction you look at it from), due to Mozilla's putting good engineering principles ahead of marketing and pulling in proven pieces of Rust code from Servo piecemeal, most people will likely never know. The best we can hope for is not that it's just a win, but that it's such a large, obvious win that when people go "How is Firefox so awesome"? the answer is Rust. That's a tall order to fill. :/

" putting good engineering principles ahead of marketing and pulling in proven pieces of Rust code from Servo piecemeal, most people will likely never know"

That's really not a good strategy. At work I can't just start using Rust without justification but if I can point at large projects being written in Rust suddenly has credibility.

For marketing a language? No, unless you ruthlessly capitalize on every small change.

For iterating on large changes to a stable secure web browser used by many millions? It seems to have worked well for them so far.

The problem is that if Rust doesn't establish itself in the broader market then the effort of developing it and adding to the browser is pretty questionable. You generally don't want code in a language nobody else uses.

I hope rust will make it but it's very hard to establish a language long-term.