title: How to write a simple receive loop in Erlang
body: <p>Let's suppose that I have 2 processes in Erlang, and each process has a receive loop running.  I want to send a signal from ProcessB to ProcessA but ProcessA doesn't actually need to do anything with it.  ProcessA only needs to know that ProcessB sent the message.  </p>
  
  <p>Here's how I have it implemented currently:  </p>
  
  <pre><code>receive   
      {message_from_process_b} -&gt;  
          io:format("received a message from b", []);  
  end,  
  %% at this point I know that I've received the message from B.  
  </code></pre>
  
  <p>It works fine.  But out of curiosity, how can I write this without the <code>io:format</code> line?  (I need Process A to block until receiving the message from B, this is part of a larger Yaws / Yapp and the server needs a response before it can show the page.)</p>