Did you think rust doesn’t free up memory for you? That would be the biggest memory leak in history! No! Rust does reference counting, it just makes sure that that number is always one! What did you think the borrow checker was for?
There is no runtime garbage collection in Rust. Given a legal program, it can detect where free-type instructions are needed at compile time, and adds them. From there on it works like C, but with no memory leaks or errors because machines are good at being exactly correct. If you want to say that’s just a reference counting algorithm that’s so simple it’s not there, sure, I guess you can do that.
Roc has runtime overhead to do garbage collection, it says so right on their own page. It might be a post-Rust language but this feels like the same conversation I’ve had about D and… I can’t even remember now. Maybe Roc is a cool, innovative language. It’s new to me. But, it doesn’t sound like it’s doing anything fundamentally new on that specific part.
Edit: Reading your follow up to the other person, it sounds like it has both a Rust-style compile time algorithm of some sort, and then (reference count-based) garbage collection at run time for parts of the program that would just be illegal in Rust.
Roc has runtime overhead to do garbage collection, it says so right on their own page.
I was sceptical about your assertion because the language authors made a design decision not do do garbage collection. So I did a google search for garbage on roc-lang.org to try and find evidence of your claim. It doesn’t say it does garbage collection. It does say overhead, but you’re talking about it like it’s a big slow thing that takes up time and makes thread pauses, but it’s a small thing like array bounds checking. You do believe in array bounds checking, don’t you?
So no, that’s not what it says and you’re using the phrase garbage collection to mean a much wider class of things than is merited. Garbage collection involves searching the heap for data which has fallen out of scope and freeing that memory up. It’s slow and it necessitates pausing the main thread, causing unpredictably long delays. Roc does not do this.
Here’s what the website actually says on the topic.
Roc is a memory-safe language with automatic memory management. Automatic memory management has some unavoidable runtime overhead, and memory safety based on static analysis rules out certain performance optimizations—which is why unsafe Rust can outperform safe Rust. This gives Roc a lower performance ceiling than languages which support memory unsafety and manual memory management, such as C, C++, Zig, and Rust.
Just in case you missed it, that was unsafe rust that lacks the overheads. If you’re advocating for using unsafe to gain a tiny performance benefit, you may as well be writing C, or zig, which at least has some tools to cope with all that stuff.
When benchmarking compiled Roc programs, the goal is to have them normally outperform the fastest mainstream garbage-collected languages (for example, Go, C#, Java, and JavaScript)
Just in case you missed it, roc is not in the list of garbage collected languages.
The bigger benefit is tailoring memory management itself based on the domain. For example, nea is a work-in-progress Web server which performs arena allocation on each request handler. In Roc terms, this means the host’s implementation of malloc can allocate into the current handler’s arena, and free can be a no-op. Instead, the arena can be reset when the response has been sent.
In this design, heap allocations in a Web server running on nea are about as cheap as stack allocations, and deallocations are essentially free. This is much better for the server’s throughput, latency, and predictability than (for example) having to pay for periodic garbage collection!
Summary: roc doesn’t have the performance disadvantages of garbage collected languages because it’s not a garbage collected language.
Just in case you missed it, that was unsafe rust that lacks the overheads.
It says some overheads. It’s different overheads, because Rust does not have reference counting garbage collection, even when safe.
Either you should go back and read what I said about reference counting being a runtime garbage collecting algorithm, or I think we’re just done. Why say more if it’s ignored anyway?
Well if you’re calling any form of automatic memory management garbage collection, then it’s only C that doesn’t have garbage collection.
Rust does have explicit reference counting with Rc<T> and Arc<T>.
I’m trying to explain to you that static analysis that limits references to one can be done in a similar way without the limit of one (especially with the assumption of immutability) whilst retaining in-place mutation where the count really is one. It upsets you when I try to explain that it’s a generalisation of the borrow checker (without the programmer pain) by calling the borrow checker a static (compile time) reference counter with a limit of one. I’m making a comparison. But don’t be surprised if a lot of programming languages implement their boolean variables as an unsigned int with a maximum of one.
If roc does the equivalent of putting a call to drop where there were two or three references that fell out of scope rather than one, in what sense is that more overhead than rust calling drop when one reference went out of scope? Rust is still “garbage collecting” the references that turned up on the RHS of assignment statements as it goes along.
The overhead we’re talking about with reference counting is like DEC rBRZ. It’s like array bounds checking. Yes, it’s an overhead, but no, it’s not worth making a big deal about it if you get to allocate arrays of sizes unknown at compile time or you get to make multiple references without messing with keywords and reference symbols, fighting the borrow checker all day long or manually adding clones.
It says some overheads. It’s different overheads,
What? Overheads are overheads. Either they’re small and useful like roc’s reference counting when it turns out to need to be at runtime or array bounds checking, or rust calling drop when some variable falls out of scope, or they’re big, stop the main thread at random points and take a long time, like garbage collection in garbage collected languages like java.
Why say more if it’s ignored anyway?
I know - I wrote a whole bunch of stuff and this other person just ignored every single nuance and explanation and kept saying the same thing again and again without trying to understand a new thing they didn’t know about before, just repeating their favourite criticisms of other programming languages whether they applied or not. Oh wait, that was you.
There is no runtime garbage collection in Rust. Given a legal program, it can detect where free-type instructions are needed at compile time, and adds them. From there on it works like C, but with no memory leaks or errors because machines are good at being exactly correct. If you want to say that’s just a reference counting algorithm that’s so simple it’s not there, sure, I guess you can do that.
Roc has runtime overhead to do garbage collection, it says so right on their own page. It might be a post-Rust language but this feels like the same conversation I’ve had about D and… I can’t even remember now. Maybe Roc is a cool, innovative language. It’s new to me. But, it doesn’t sound like it’s doing anything fundamentally new on that specific part.
Edit: Reading your follow up to the other person, it sounds like it has both a Rust-style compile time algorithm of some sort, and then (reference count-based) garbage collection at run time for parts of the program that would just be illegal in Rust.
I was sceptical about your assertion because the language authors made a design decision not do do garbage collection. So I did a google search for garbage on roc-lang.org to try and find evidence of your claim. It doesn’t say it does garbage collection. It does say overhead, but you’re talking about it like it’s a big slow thing that takes up time and makes thread pauses, but it’s a small thing like array bounds checking. You do believe in array bounds checking, don’t you?
So no, that’s not what it says and you’re using the phrase garbage collection to mean a much wider class of things than is merited. Garbage collection involves searching the heap for data which has fallen out of scope and freeing that memory up. It’s slow and it necessitates pausing the main thread, causing unpredictably long delays. Roc does not do this.
Here’s what the website actually says on the topic.
https://www.roc-lang.org/fast
Just in case you missed it, that was unsafe rust that lacks the overheads. If you’re advocating for using unsafe to gain a tiny performance benefit, you may as well be writing C, or zig, which at least has some tools to cope with all that stuff.
https://www.roc-lang.org/fast
Just in case you missed it, roc is not in the list of garbage collected languages.
https://www.roc-lang.org/platforms
Summary: roc doesn’t have the performance disadvantages of garbage collected languages because it’s not a garbage collected language.
It says some overheads. It’s different overheads, because Rust does not have reference counting garbage collection, even when safe.
Either you should go back and read what I said about reference counting being a runtime garbage collecting algorithm, or I think we’re just done. Why say more if it’s ignored anyway?
I don’t think I’m the zealot here.
Well if you’re calling any form of automatic memory management garbage collection, then it’s only C that doesn’t have garbage collection.
Rust does have explicit reference counting with Rc<T> and Arc<T>.
I’m trying to explain to you that static analysis that limits references to one can be done in a similar way without the limit of one (especially with the assumption of immutability) whilst retaining in-place mutation where the count really is one. It upsets you when I try to explain that it’s a generalisation of the borrow checker (without the programmer pain) by calling the borrow checker a static (compile time) reference counter with a limit of one. I’m making a comparison. But don’t be surprised if a lot of programming languages implement their boolean variables as an unsigned int with a maximum of one.
If roc does the equivalent of putting a call to drop where there were two or three references that fell out of scope rather than one, in what sense is that more overhead than rust calling drop when one reference went out of scope? Rust is still “garbage collecting” the references that turned up on the RHS of assignment statements as it goes along.
The overhead we’re talking about with reference counting is like
DEC rBRZ. It’s like array bounds checking. Yes, it’s an overhead, but no, it’s not worth making a big deal about it if you get to allocate arrays of sizes unknown at compile time or you get to make multiple references without messing with keywords and reference symbols, fighting the borrow checker all day long or manually adding clones.What? Overheads are overheads. Either they’re small and useful like roc’s reference counting when it turns out to need to be at runtime or array bounds checking, or rust calling drop when some variable falls out of scope, or they’re big, stop the main thread at random points and take a long time, like garbage collection in garbage collected languages like java.
I know - I wrote a whole bunch of stuff and this other person just ignored every single nuance and explanation and kept saying the same thing again and again without trying to understand a new thing they didn’t know about before, just repeating their favourite criticisms of other programming languages whether they applied or not. Oh wait, that was you.
Interesting.