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by tjoff 22 days ago
GC is such a mistake though, you don't have to use rust but to never have to think about memory is a disservice to the programmer. Because that is something you always should do, and if you do then GC is nothing but a hindrance.

For scripting etc. it is perfect though.

3 comments

Even if you're one of those people who believes the highest levels of performance require manual memory management (I'd disagree, but whatever), you'd do well to consider the performance of real-world GC against performance of the Arc/Box/dyn/clone-heavy "high-level Rust" [1] [2] that people and LLMs usually write.

Maybe you can write a carefully-tuned arena-and-slotmap that beats the pants off any GC. GC doesn't have to compete against P99.9 systems programming excellence. It has to compete against an endless soup of Arc, Box, and clone, and it will win this match without breaking a sweat.

[1] https://hamy.xyz/blog/2026-01_high-level-rust

[2] https://llogiq.github.io/2020/05/30/hi.html

Performance is not even a factor in my argument.
Why does having. GC mean not thinking about memory? I think about memory constantly in GC languages because I still want it to perform well.

The biggest difference is the failure modes. If I'm not thinking about memory, my RSS is higher or a bit of extra CPU time goes to GC. Both of those are radically better than UAF or buffer overruns. Good trade IMO.

I didn't say that. But if you think about memory then GC does more harm than good because you have no help from the language.

A GC is not the only fix for UAF and buffer overruns...

Depends very much which programming languages we're talking about.

There are enough managed languages with knobs allowing to do C like coding when required to do so.

Which is about as convenient as opt-in types in python. Nice to have but but a poor substitute and requires much more diligence than if it was designed for it in the first place.
That really, really depends on the language.
It is perfectly convenient across D, Modula-2+, Modula-3, C#, Nim, Swift, Oberon, C++/CLI, and plenty others.
For a lot of programming tasks, HAVING to think about memory is a disservice.

That's part of the reason why Python, go, Ruby, etc. are so popular.

There is no one right answer, it's very dependent on what's being built and where the ROI for the programming effort comes from.

For some tasks, sure.

But you still have to think about memory in those languages.