Object Oriented Programming in APL2

In both the procedural and the non-procedural cases, the basic unit of execution is the program. The data only provide values that will be used to perform computations or to decide the order of execution. A given application is a hierarchical set of programs (modules) each of which is capable of invoking other programs in the hierarchy. The data may be global (accessible from every program in the hierarchy) or local (accessible by the program where they belong and, sometimes, by those at a lower level in the hierarchy).