I've recently spent the past few days writing a higher-level wrapping around gRPC Core (attempting to keep everything as safe as possible), and have reached a point where technical demos are possible. There are definitely some bugs that I have to work out (and LOTS of code to document.. this was mostly an experiment to see if it would work or not), but I'd definitely like to get the community's take and help on maintaining this library.

Currently, bidirectional streaming (server <-> client) is broken for an unknown reason, but client OR server streaming independently work great (using Fibers!). The library is highly multi-threaded (each "Service" has a thread spun up for it), implementing mutexes up the wazoo (the majority of which I definitely think are unnecessary, but there is very little documentation for gRPC Core which specifies memory safety..). As well, the client-side has not been fully finished (rather, I've been focusing much more on the server side as it's easier to debug), however, the library is usable at it's current state (while being a little rough due to lots of debugging "writeln"s being all over the place), and it requires a modified version of the protobuf compiler written by Dracos Carp. You can pull a rudimentary version of the library from here: https://github.com/hatf0/grpc-d, with the forked protobuf compiler being available here: https://github.com/hatf0/protobuf-d, and the gRPC "greeter" example available here: https://github.com/hatf0/grpc-demo.