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Comment by 0xdeafbeef | Hacker News Reader

What the point, though? You will get compiling code, but later you would need to reachitecture code to avoid violating rust rules.

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Sometimes, you just need to know if an idea will even work or what it would look like. If you have to refactor half the codebase (true story for me once), it makes the change a much harder sell without showing some benefits. IE, it keeps you from discovering better optimizations because you have to pay the costs upfront.

Can't you usually just throw some quick referenced counted cells in there, to make the borrow checker happy enough for a prototype without refactoring the whole code base?

In Rust, it's a lot easier to refactor half the codebase than it would be in another language. Once you're done fighting the compiler, you're usually done! instead of NEVER being sure if you did enough testing.

I can’t tell if you missed the whole point of “exploratory”…

I don't know either. Personally I can spend days or more on exploratory efforts that end up scrapped. My source code is usually version controlled, so I never have to worry about messing things up. But I suppose not everyone has this kind of time for stuff that isn't guaranteed to pan out.

Sometimes I will prototype an exploration in another crate or module so I can see if there are performance gains in a more limited application. Sometimes these explorations will grow into a full rewrite that ends up better than if I had refactored.

> Sometimes, you just need to know if an idea will even work or what it would look like.

I think what GP is trying to say is that the value of such exploration might be limited if you end up with something incompatible with "proper" Rust anyways.

I suppose it depends on how frequently "transition through invalid Rust while experimenting and end up with valid Rust" happens instead of "transition through invalid Rust while experimenting and end up with invalid Rust", as well as how hard it is to fix the invalid Rust in the latter case.

In my case, I was adding a new admin api endpoint, which meant pulling through a bunch of stuff that was never meant for the api and got in a fight with the borrow checker. For me, I just wanted to see if I broke something on a feature level (it was never meant to be exposed by the api after all), and I didn’t care about memory safety at that point. Refactoring it properly just to get memory safety just to see what would have broke, ended up breaking out of my time-box, so it never saw the light of a merge request. Had I been able to prove the concept worked, I would have opened a PR and against the open issue to find out the best way to refactor it “properly” into a right way. As it was, I would need to completely guess what the right way was without ever even knowing if the idea would work in the first place.

I guess that doesn't neatly fall into the categories I described, though I think it's closer to the former than the latter.

That being said, I think what you describe sounds like a case where relaxed checks could be beneficial. It's the eternal tradeoff of requiring strong static checks, I suppose.

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