lib/repeatable/expression/base.rb in repeatable-0.5.0 vs lib/repeatable/expression/base.rb in repeatable-0.6.0

@@ -22,9 +22,25 @@
           NotImplementedError,
           "Don't use Expression::Base directly. Subclasses must implement `#to_h`"
         )
       end
 
+      def union(other)
+        Union.new(self, other)
+      end
+      alias + union
+      alias | union
+
+      def intersection(other)
+        Intersection.new(self, other)
+      end
+      alias & intersection
+
+      def difference(other)
+        Difference.new(included: self, excluded: other)
+      end
+      alias - difference
+
       private
 
       def hash_key
         self.class.name.split('::').last
           .gsub(/(?<!\b)[A-Z]/) { "_#{Regexp.last_match[0]}" }