Yes and no, depending on which aspect of the language you consider:
- Type system -> OCaml is more modern (despite being designed before Go)
- Concurrency, parallelism, garbage collector, tooling -> Go is more modern (Reason is improving the tooling with refmt for example; work is ongoing on parallelism)
As far as I know, there is nothing fancy about it, except for the fact that a lot of work has been put into Go's garbage collector, especially in versions 1.5 and 1.6, with people working full-time on it.
Go easily achieves GC latencies well below 10 ms, even for programs using a large heap, without having to manually "tune" the GC.
