I’d say the majority of Nim’s stdlib can be used without ref (arc) types. The compiler only generates ARC code if you use ref types not when you import a module.

Yeah much of the basic stdlib only uses vector, string, and map types which are similar to C++ & Rust ones with single ownership and move semantics. Static arrays can be used with many basic functions like sort.

The JSON module in Nim’s stdlib does use ref ARC types. However neither C++ nor Rust provide a JSON module by default.

Actually, a fair bit of Nim’s stdlib can even be used without allocators! Unlike Rust’s #[no_std] for embedded which is just a pain.