[woolvalley]

Graphs are OK in reference counting languages like swift / objective-c, it doesn't have to be done with a GC.

I think you could use Rc<Thing> in rust too if you want to solve it using rust, but then you have "swift with more boilerplate" as one friend said.

[rwmj]

Ref counting is a poor kind of garbage collection. In particular it has a very large overhead: typical GC has an overhead of a couple of bits per allocation, but ref counting usually wants to allocate an extra word (eg. 32 or even 64 bits) per allocation.

Another actually more serious problem is that typical ref counting implementations mix the allocated data with the references, so that when you inc/dec the reference you dirty a cache line containing the data. There exist implementations which improve on this by storing the references in a separate part of memory, but they are not how it's commonly implemented.