[ReneSac]

ARC in Nim does not mean the same thing as in Rust. I'm still not fully up to speed on ARC/ORC nor went very far on Rust, so I might be wrong here, but from what I understand:

In Nim using ARC/ORC the compiler statically checks the memory usage, possibly helped by lent and sink annotations (similar to borrow and lifetime annotations in Rust, but not as powerful yet) and for what can't be proved statically it adds reference counting. And even under ARC you will probably be using stack allocations a lot in Nim.

I think the main difference between Rust and Nim approaches to memory management is opt-in vs opt-out. In Rust you are forced from the start to think about it and be more explicit about it, while in Nim the lifetime annotations are more like optional optimizations that may be added gradually to help the compiler, that might otherwise be adding reference counting and copies behind your back to maintain correctness.

For some use cases, being forced from the start to think in a lower level of abstraction is helpful and makes the performance more predictable and transparent. People still use C partially because of that. But I like Nim's approach where I can use it as productively as an scripting language avoiding premature optimization, but can easily delve as low level as I want to write a keyboard firmware or GBA game.