I'm surprised Facebook doesn't use more Go. Everyone I talk to from Facebook seems to love Go--no idea why they don't use it more widely. Facebook doesn't strike me as the sort of company to not use a programming language just because its rival (Google) is in the driver's seat. Go is still open source.
I know Facebook has some D advocates, but D doesn't seem to be too popular among the programmers I know. I haven't looked too deeply at it myself, but it seems to be a language more interested in taking the job of Rust and C, rather than the job of Python and Ruby. So there is no reason Facebook can't pursue both languages as a company.
Creating a new language is a big effort that requires a lot of expertise. Why would they create a new language if there's one that they already like and want to use?
Funny that the original intent for the Go creators was to not have to write C++[1] -- which of course is in the C/C++/Rust/D space -- and that Rob Pike seemed surprised that more C++ programmers didn't make the switch.
The two languages seem to diverge when it comes to the fact that Walter Bright seems to like to write both expressive and high-performance code (meaning, at the same time). That kind of philosophy tends to lead to iterators, generators[2] etc. which Go seems to look at as superfluous -- just write a for loop, more or less.
[1] Write C++ for the particular software that they make, anyway.
There should be description fields or some kind of readme files for the profiles on GitHub. I can only assume that what I'm looking at is a set of tools written in/for Go language that are used by Facebook. Right?
