WARaft: An Erlang implementation of RAFT

There are at least four more Raft implementations in Erlang, ranging from Ra (RabbitMQ), to rafter (Andrew J. Stone), to zraft_lib (Dreyk), and huckleberry (0xYUANTI). How WARaft compares to them?

Possibly very interesting (production usage at WA sounds rather interesting) but it really does not say much.

Okay so what is RAFT?