Time of day as conditional in Vim

I'm working on improving my .vimrc, and I want to have command inside of it that depends upon whether it is night or day. I'd like to have something like the following in the end:

if isNightTime
  " do something
else
  " some other thing
endif

What's the best way to go about this?

Using the strftime() funtion is probably the best approach. If you are satsified with one-hour resolution, you could do something like this:

let hour = strftime("%H")
if 6 <= hour && hour < 18
    " do daytime stuff
else
    " do nighttime stuff
endif

See

:help strftime()

and the strftime man page.