client.cr

require "socket"

UNIXSocket.open("/tmp/cr.sock") do |sock|
  puts "What is your name?"
  name = gets
  sock.puts name
  puts sock.gets
  sock.close
end

server.cr

require "socket"

server = UNIXServer.new("/tmp/cr.sock")

while sock = server.accept 
  proc = ->(sock : UNIXSocket) do
    spawn do
      name = sock.gets
      puts name
      sock.puts "Hello #{name}."
      sock.close
    end
  end
  proc.call(sock)
end