function duckTypeClause(previousExpr, detection) {

      var fieldListStr = detection[FIELD_LIST_INDEX];

      if (!fieldListStr) 
         return previousExpr; // don't wrap at all, return given expr as-is      

      var hasAllrequiredFields = partialComplete(
                                    hasAllProperties, 
                                    arrayAsList(fieldListStr.split(/\W+/))
                                 ),
                                 
          isMatch =  compose2( 
                        hasAllrequiredFields, 
                        headNode
                     );

      return lazyIntersection(isMatch, previousExpr);
   }
Create an evaluator function for a a duck-typed node, expressed like:

   {spin, taste, colour}
   .particle{spin, taste, colour}
   *{spin, taste, colour}