Getting side tracked seems to be a fact of life. This morning it is C++ Unikernels. A variety of unikernels.
This all happened while looking at this years CPPCon 2017 show schedule There is a session on includeOS, which is a performant, minimal unikernel operating system for the cloud. We provide a bootloader, standard libraries and the build- and deployment system. Written and used for C++ apps. And has some references to code for small, light weight http servers, ostensibly probably for REST interfaces. Even LWN has a recent discussion about it.
Also in the program, immer: a library of persistent and immutable data structures written in C++. These enable whole new kinds of architectures for interactive and concurrent programs of striking simplicity, correctness, and performance.
Somewhere along the line, Nix: the purely functional package manager, a part of the purely functional Linux distribution was mentioned.
... the Nix package manager from a description in a purely functional build language. The fact that it’s purely functional essentially means that building a new configuration cannot overwrite previous configurations.