> It definitely looks like data. But it can be made into code using an appropriate macro. to chime in, it also can be made into 2 systems - one which defines '

> It definitely looks like data. But it can be made into code using an appropriate macro. to chime in, it also can be made into 2 systems - one which defines 'book' as an in-memory object which can be inspected, and one which, say, defines a remote database object - your 'language spec' is the syntax, and you can implement multiple implementations, or replace subsystems as you build up the bigger thing - e.g. 'now my hashtables are persisted to disk', etc