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> Rewriting something for no reason will for sure turn mature developers off. I've yet to hear a good reason for why you're proposing this rewrite. I'm sure it'll be perceived as very modern and "relevant" though.

Fish has been lovingly maintained by a small group of developers for a long time, and it's an excellent piece of software. The person proposing the Rust port has been the chief maintainer a long time.

I don't think you understand the credibility they have with longtime users and contributors.

Not the GP, but I want to point out that while I respect the chief maintainer and not doubt their credibility with fish's users, no one is immune to mental fallacies.

GP's comment points out where there's gaps in thinking/logic in the arguments made to do the port.

Personally I think the maintainer would've done well both to the community and oneself if the reason given was

> Hey, I'm bored, I want to practice Rust and want to do something fun, so I'm doing this.

than cloak it with some weak sauce reasons.

Why isn't using a language that has a growing community of young developers not a "reason"? They're looking towards the future and making the bet that it will be easier to get new contributors in Rust than in C++. Maybe you disagree with the prospective future of C++, or the feasibility of rewrites, but it hardly seems like "not a reason" to peruse something like this, it seems like a pretty strong one, since as you say "finding good C++ devs is hard" and they're interested in growing the number of contributors in the future.

Because, while the sequence "100,000 100,000 100,000 100,000" is stable and "1 2 3 4" is growing, that does not mean that the latter will eclipse the former anytime soon - the point being implied by TFA

I seriously doubt there are 5 orders of magnitude more C++ open source contributors actively participating in projects on GitHub than Rust, which is the relevant question. Enthusiasm counts for projects like this that are looking to stay relevant.

At this point, I would love solid numbers on the number of new C++ projects (open source or otherwise) vs Rust. Google just came out indicating how well the transition was working for them with respect to memory vulnerabilities.

C++ is simply not intended for new projects in this day and age; even Carbon and cppnew are specifically designed for projects that must interoperate heavily with C++ libraries, and are thus not entirely greenfield in that sense. The Carbon developers have explicitly made it clear that new projects should be written in a safe language if at all viable.

I am watching the Carbon talk now. Successful language transitions have happened in the past when the new language is fully and easily interoperable with the old one. How easy is it to add Rust to a C++ code base? If the answer is 'not at all', then the transition is unlikely to happen anytime soon (it hasn't happened in the decade that Rust has been around). "New projects should be written in a safe language" -- what about the existing ones? Your memory safe web server isn't very useful when it's sitting on top of a kernel tcp/ip stack RCE vulnerability.

Early on, Rust’s goal was to improve Firefox, a large C++ codebase. A bunch of language design decisions were made to ensure this could work well.

However, that doesn’t mean it’s always super easy. C++ interoperated with C even more easily: just compile your code with the new compiler! With Rust, it’s more like FFI.

https://cxx.rs/ is at the forefront here.

> it hasn't happened in the decade that Rust has been around

This seems to imply that no C++ codebase has had Rust added to it. This is not true, just to be clear, there are. Firefox, for example. Chrome soon. All kinds of things. I also may have misunderstood you!

If cxx.rs is at the forefront, I'd describe autocxx and crubit as being at the bleeding edge. But they hold the promise of significant improvements in interop between Rust and C++.

Yeah, they’re very exciting too! I should start including them as well when I talk about this, thanks :)

> "New projects should be written in a safe language" -- what about the existing ones? Your memory safe web server isn't very useful when it's sitting on top of a kernel tcp/ip stack RCE vulnerability.

The best time to start rewriting everything in an ML-family language was 20 years ago; the second-best time is today.

I'm highly skeptical that ML will take over everything. ML is great for cases where being "sometimes wrong" or "approximately correct" is acceptable. It's not acceptable for the vast majority of computer science problems however. If there are many correct answers then ML is a good use case. If there is only one correct answer then ML will never be used there.

Edit: I assumed that "ML" here stood for Machine Learning, it appears that was not the case.

ML the programming language family, not machine learning.

> How easy is it to add Rust to a C++ code base? If the answer is 'not at all',

Its not clear that you even read the linked post on GitHub before commenting.

The first post in that GitHub thread says: "This should be thought of as a "port" instead of a "rewrite" because we would not start from scratch; instead we would translate C++ to Rust, incrementally, module by module"

> then the transition is unlikely to happen anytime soon (it hasn't happened in the decade that Rust has been around)

As of a year ago, 10% of FireFox had been ported over (https://news.ycombinator.com/item?id=30744057). This is the overall effort started in 2014 https://wiki.mozilla.org/Oxidation

https://madnight.github.io/githut/#/pull_requests/2022/4

This can show you certain data. I’ve linked to Q4 2022, specifically PRs opened. You can see C++ at #4 with 9.7% of PRs, and Rust at 14 with 1.6%.

Rust users are also going to be biased towards GitHub over other places.

The tremendous drop in javascript over 2021 is very interesting.

I'd assume that's a massive shift to TypeScript, but yep!

Respect for providing data and being centered despite being a core Rust dev.

Thank you. To be clear, I am not involved with the development of Rust anymore.

As an old C/C++ dev I'm beyond excited to re-tool as a Rust dev. It's such a pleasure to use compared to C++.

Fish porting itself to Rust makes me more likely to contribute to it in the future.

/anecdata

It’s his project. He sees it that way, as do others. You see it differently. The objective truth is probably somewhere in between.

Other projects have seen a significant positive impact after switching to rust. I hope fish shell also sees that impact, regardless of any feelings around rust.

As fish user, I can be concerned that a rewrite like this might ruin a project, and consequently oppose such rewrite. Doesn't matter whose project it is. If you think I should just ignore it and "accept decision" - this is when it's clear, that what you really mean is "you just should not care".

As a fish user, I'd be concerned about the opposite - having a burden of a big c++ codebase and all it's build shenanigans to maintain which is not fun at all anymore could lead to the project becoming stale, especially with a low bus factor.

Plus, it could gain new external contributors. Heck, I'd consider contributing myself now whereas I wouldn't consider wasting my time on doing c++ for fun unless it was mission critical for some reason

My thoughts exactly. Why would the implementation language bless a piece of software as ‘relevant’? I’d also argue learning how to do for loops in bash, which would let you write them on about any server in any data center on the planet, would serve one much better.

> How is it becoming a legacy language? This is completely false and unsubstantiated. Yeah, finding good C++ devs is hard, the thing takes skill.

If getting good developers that know technology X is hard and getting harder over time (which I think is definitely true about C++), this on its own will cause technology X to become legacy.

Something being cool and modern matters a lot more than you seem to believe.

Rust is a great language and it's growing in popularity. It's a good choice to get experience with Rust, grow their community and improve the codebase.

It would be like trying to run a FOSS project in COBOL. No one wants to do that for fun. The bank manages by paying people a fortune to do something they don't want to do.

I agree, yet I think rewriting - even for no reason at all - can make the thing better.

https://www.joelonsoftware.com/2000/04/06/things-you-should-...