What's so good?

• E.g. a PDC Prolog domain (type) definition:

      tree = t( tree, integer, tree ); empty
  

• No pointers to manipulate, recursive or nested definitions no problem.
• You can show the structure patterns anywhere in your code (no need to set values field by field):

      ...
      MyCar = car("blue","chevy",1957,engine(327,supercharged),asking_price(12995)),
      sell( MyCar, AgreedPrice ),
      ...