[janAkali]

1. Nim uses 'var' modifier to pass by reference, e.g. "proc (n: var int)...", default behaviour is pass by value. And there're also raw pointers and references (safe pointers).

>is a no-gc mode available?

You can disable gc, but most of standard library depends on it. But in Nim 2.0 there's finally support for ARC and ORC (ARC + cycle collector).

[ElegantBeef]

> default behaviour is pass by value

Is not exactly true, smaller than 24 bytes is passed by value, the compiler optimizes larger calls and passes by reference implicitly.

[msk-lywenn]

I've been searching and can't find it: A in ARC is for automatic, what does the O stand for?

[dinHeld]

O is a visual pun because it adds a cycle collector to ARC.

[lambertsimnel]

I assumed the O was for "optimised", but apparently it stands for "cycle":

https://nim-lang.org/blog/2020/12/08/introducing-orc.html