IncludeOS? [0]
From the CppCon 2016 presentation description:
"Early in the design process we made a hard choice; no C interfaces and no blocking POSIX calls. We’ve done everything from scratch with modern C++ 11/14 - Including device drivers and the complete network stack all the way through ethernet, IP and ARP, up to and including UDP, TCP and recently also an http / REST API framework. To achieve maximum efficiency we decided to do everything event based and async, so there's plenty of opportunities to use lambdas and delegates." [1]
[1] https://cppcon2016.sched.org/event/d30a43dae4a490dce81a3dfc6...