s or part
characters are available at any one time (although if &rsquo;port&rsquo;
references a socket, it should be non-blocking for this to be
guaranteed).  It is intended to be called within a waitable procedure
invoked by a-sync (which supplies the &rsquo;await&rsquo; and &rsquo;resume&rsquo; arguments),
and this procedure is implemented using a-sync-read-watch!.  If an
exceptional condition (&rsquo;excpt) is encountered, #f will be returned.
If an end-of-file object is encountered which terminates a li