Techniques for avoiding conditional execute in APL2

Abstract

Execute ( ) is unique among the APL2 primitive functions in that it is the only one which does not necessarily produce an explicit result. This makes it convenient for executing an APL expression conditionally. Execute is also unique in that it is the only symbolic primitive which permits only a character argument. This tends to produce awkward programming.This paper will look at ways to avoid the use of conditional execute by suggesting alternate methods and ways of thinking which are unique to APL. These methods have been used to great advantage in production code.Most examples of code used in this paper have been taken from an actual APL2 application. Although most of the examples are in APL2, many will work in other APL dialects. Some minor modifications have been made to the code in the interests of security and clarity. Most of these involved changing the names of some functions or variables.