[foldr]

You’d want a garbage collector in Rust for the same reason you’d want it in any other language. Manual memory management adds code complexity and can often be slower. Arena allocators only work in certain situations and considerably complicate management of lifetimes.

> , but if you touch the upper ceiling in go program, there is not much you can do about it

I’m not seeing this. There’s lots you can do to optimize Go code. Could you give a concrete example?