The coupling in PID 1 is a bit much. I actually quite like systemd-networkd for some use cases, though. It lets me declaratively manage the network interfaces on my headless servers in a way that’s very similar to how I’m managing the services. Sure, it’s coupled to systemd, but it’s mostly one-way coupling; if I want to use NetworkManager (which I do on my laptop), I can switch over, and nothing in the init system breaks.

If type constraints later in the function let the compiler infer the type, this syntax totally works.