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Comment by shepmaster | Hacker News Reader

It's not a blog, but Rust Belt Rust 2017 [1] (a conference I help organize) will have a talk "The Story of Stylo: Replacing Firefox's CSS engine with Rust" [2]. The conference is in Columbus, Ohio, and is reasonably priced.

[1]: http://rust-belt-rust.com/ [2]: http://rust-belt-rust.com/sessions.html

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Are there any stats yet on improvements in memory safety within Firefox attributable to Rust. In theory, it could be as much as 50% fewer based on the original premise of Rust removing whole classes of programmer errors, but are there stats from Rust being in the wild? The CSS replacement reminded me that there should be something to compare.

> are there stats from Rust being in the wild?

I don't know, but if I recall correctly, nobody has ever reported a memory safety bug to ripgrep, or even the underlying regex engine. I don't really know how many people use ripgrep, but it's not zero.

I can assure the lower bound is at least one. Thanks for boosting my productivity!

I use it everyday, several times per day. Thank you for you such a useful utility.

Well, everyone who's using VS Code is using ripgrep, and a year ago Microsoft said it had half a million active users, and the number has presumably grown since then.

Doesn't ANY rewrite (regardless of whether there is a change in language) reduce bug-count, simply because all the requirements are more clear in advance and the engineers have had more time to think about a suitable architecture?

Nope. Churn (= number of lines changed) is actually pretty well correlated with bug count.

I don't have a precise reference off-hand, but I believe I read it in "Making Software: What Really Works, and Why We Believe It".

Obviously you'll probably get closer to what the software is intended to do, but it probably won't reduce bug count in the short term. In the long term, you might end up with fewer lines of code overall (which is also correlated with overall bug count).

> Churn (= number of lines changed) is actually pretty well correlated with bug count.

Is a rewrite considered as bunch of line changes or not? I would say not.

Also, can I assume that by "correlated with" you mean "positively correlated with"?

If so, isn't a rewrite reducing bug count because you'll end up with far fewer "changed" lines?

I would assume a rewrite counts as a bunch of line changes -- absent evidence to the contrary. Obviously, if you're changing the language that changes the equation, some bugs which can happen in C++ simply cannot happen in Rust, for example.

(And yes, I meant "positively correlated with".)

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