ARCHITECTURE

A few notes regarding journalism's internal architecture. (Users should not care about any of these things.)

* Operations on Tables return new Tables.

* Operations on Columns return appropriate native data structures. Columns are not portable between tables!

* Tables that are instantiated with raw data will copy that data so it becomes immutable within the context of the Table.

* Tables that are forked will share Row instances for memory efficiency. This is safe because row data is immutable. Methods that create new data will copy data first. (e.g. Table.compute)

* ColumnMapping, RowSequence, Column, and Row have **read only** access to a Table's private variables. They are purely a formal abstraction and for purposes of encapsulation they can be treated as a single unit.

* Columns lazily construct a copy of their data from their parent Table and then cache it.

* Operations accept functional arguments wherever possible for maximum flexibility.