Re: Multi- Occurrence Data Structure

This seems to have evolved into a discussion of the relative merits of 3GLs vs. 4GLs, or imperative (procedural) versus declarative (non-procedural) languages.

Procedural or "imperative" languages are what most of us are familiar with -- assembler languages, COBOL, FORTRAN, PL/I, Pascal, C, etc. Using these languages, you must elaborate all of the steps needed to perform the desired tasks, step-by-step. In other words, you must specify HOW to perform the desired tasks.

Non-procedural or "declarative" languages let you specify WHAT results you want to obtain, rather than spelling out the details of how to produce those results. There are many successful 4GLs on many platforms.

RPG in its original form was a kind of 4GL, with the "cycle" -- you could produce report programs in a "declarative" way, with little or no procedural code (C-specs).
Many System/38 RPG III programmers avoided the cycle in favor of writing their own equivalents in full procedural code. This may have been done in an effort to squeeze as much performance as possible from System/38s and early AS/400 CISC models.

As RPG evolved into RPG II, RPG III and RPG IV, it seems to cater more towards procedural coding style, while not totally abandoning the "cycle" etc.