title: Can I specify my explicit type comparator inline?
body: <p>So .NET 3.0/3.5 provides us with lots of new ways to query, sort, and manipulate data, thanks to all the neat functions supplied with LINQ.  Sometimes, I need to compare user-defined types that don't have a built-in comparison operator.  In many cases, the comparison is really simple -- something like foo1.key ?= foo2.key.  Rather than creating a new IEqualityComparer for the type, can I simply specify the comparison inline using anonymous delegates/lambda functions?  Something like:</p>
  
  <pre><code>var f1 = ...,
      f2 = ...;
  var f3 = f1.Except(
             f2, new IEqualityComparer(
               (Foo a, Foo b) => a.key.CompareTo(b.key)
             ) );
  </code></pre>
  
  <p>I'm pretty sure the above doesn't actually work.  I just don't want to have to make something as "heavy" as a whole class just to tell the program how to compare apples to apples.</p>