Absolutely yes. The default GC (not ARC/ORC) is not stop-the-world.
"Nim's memory management is deterministic and customizable with destructors and move semantics, inspired by C++ and Rust. It is well-suited for embedded, hard-realtime systems."
Nim compiles to C, so you can use it as a "better C" like rust or Zig. That said, the main difference is that it comes with a GC, or more accurately, multiple GC options that are tunable. If you cannot have GC, as in embedded, you can compile without GC, but then you lose access to the vast majority of the standard library (which is similar to rust's --no-std, from my understanding).
It used to be the case that you turned the GC off when running on embedded, but you are correct that ARC/ORC runs on embedded devices and will indeed make these even easier to program against in the future. Whether running things that normally require a GC on a tiny microcontroller is a good idea is of course entirely up to the programmer.
Many people call Go a systems language, which by my reasoning means almost anything is.
Like many words programmers use, there appears to be no agreed upon definition. Memory management in Nim is not usually totally manual so may be not top notch for all systems type tasks. But you can probably do it if you need to given how configurable memory management it.
Interestingly, they claim yes – the homepage says this:
> Nim is a statically typed compiled systems programming language.
> Nim's memory management is deterministic and customizable with destructors and move semantics, inspired by C++ and Rust. It is well-suited for embedded, hard-realtime systems.
However, this article says that ORC, a non-deterministic and non-hard-realtime GC system, is likely to become the new default GC in the future.
Perhaps they found that the "systems language for hard-realtime" wasn't as compelling a value proposition as they originally thought?
Or perhaps the tradeoffs of ORC and availability of manual memory management give them confidence that it won't materially harm hard-realtime systems use-cases in practice?
> the tradeoffs of ORC and availability of manual memory management
For those not familiar with the language, Nim only uses GC for `seq` (dynamically sized lists like c++ vectors), `string`, and types declared with `ref`.
Everything else is a stack allocated value type, or as noted in the parent, you can manually manage with pointers.
> won't materially harm hard-realtime systems use-cases in practice
I think this is true. I already find myself rarely using GC when writing Nim, but when you want it, it's nice yet painless.
Later they compare no async, and ORC with async and find that it's "only a few ms slower than the RPC calls running with ARC and no async."
While this example may not be the hardest of realtime, it does show that ORC competes with manual approaches to memory management in constrained environments.
It can, ARC is really not a full-blown GC (people usually associate GC with a tracing garbage collector which ARC is not). ARC is fully suitable for writing any low-level stuff such as OSes and similar.
