d call reply with 
   timeout set to <em>-1</em> (<em>wait eternally</em>).
   There may be situations, however, where it actually
   makes sense to restrict the waiting time,
   <em>i.e.</em> to perform some housekeeping in between.
</p><p>Typically, you call reply in a loop like
</p><pre> forever $ reply srv (-1) nullType [] f
</pre><p>where <em>f</em> is a function of type 
</p><pre> Message i -&gt; IO o.
</pre><p>Parameters:
</p><ul><li> <code><a href="Network-Mom-Stompl-Patterns-Basic.html#t:ServerA">S