As someone who's done a lot of functional and OO programing over the years, I find it very hard to believe that you have multiple projects that went from 1K+ lines of C++ to 10 lines of Scala.
Claims like this are the sort of thing that make make it hard to convince people to try functional programming, because they think that FP evangelists are full of shit.
In C++ I implemented a lot of functionality by hand using mostly glibc and stl. In scala there are library's to help with threading and network I/O in my case it was A combination of threading (Akka), Network I/O (again Akka) and HTTPS communication (dispatch-http). So yes this was a combination of a better programing style and better support for libraries (SBT)
Claims like this are the sort of thing that make make it hard to convince people to try functional programming, because they think that FP evangelists are full of shit.