Talk to ZMQ through channels.
cd network-zmq-unagi nix develop # run this whenever `package.yaml` changes hpack cabal build cabal test # use blocking channels; send 1 message each from two different threads cabal run main -- b 1 # use non-blocking channels; send 1 message each from two different threads cabal run main -- nb 1 # use non-blocking channels; send 25000 messages each from two different threads cabal run main