[nem-en] usesite

[Vladimir Reshetnikov]

What does 'usesite' mean here (core.n):

  [Nemerle.MacroUsage (Nemerle.MacroPhase.WithTypedMembers,
                       Nemerle.MacroTargets.Class,
                       Inherited = false, AllowMultiple = false)]
  macro StructuralHashCode (t : TypeBuilder) {
    def flds = t.GetFields (BindingFlags.Public %| BindingFlags.NonPublic %
|          
                            BindingFlags.Instance %| BindingFlags.DeclaredOnly);

    def body = 
      List.FoldLeft (flds, <[ 0 ]>, fun (x : IField, acc) {
        <[ $acc %^ $(x.Name : usesite).GetHashCode () ]>
      });
    t.Define (<[ decl:
      public override GetHashCode () : int {
        $body
      }
    ]>);
  }