go_channel.ex

defmodule GoChannel do
  def make do
    spawn(&GoChannel.server/0)
  end

  def write(channel, val) do
    send(channel, { :write, val})
  end

  def read(channel) do
    send(channel, { :read, self })
    receive do
      { :read, channel, val} -> val
    end
  end

  def server do
    receive do
      { :read, caller } -> receive do
                     { :write, val } -> send(caller, { :read, self, val }); server
                   end
    end
  end
end

test.exs

defmodule GoChannelTest do
  use ExUnit.Case

  test "write and read to a channel" do
    channel = GoChannel.make
    GoChannel.write(channel, 'hello')
    assert GoChannel.read(channel) == 'hello'
  end

  test "write and read preserves order" do
    channel = GoChannel.make
    GoChannel.write(channel, 'hello')
    GoChannel.write(channel, 'world')
    assert GoChannel.read(channel) == 'hello'
    assert GoChannel.read(channel) == 'world'
  end
end