This package provides a predefined instantiation of the table abstraction for type Standard.Boolean. The null value is False, so the only non-null value is True, i.e. this table acts essentially as a set representation. This package is based on Macro-SPITBOL created by Robert Dewar.

package GNAT.Spitbol.Table_Boolean is new
  GNAT.Spitbol.Table (Boolean, False, Boolean'Image);