Operators considered harmful

Abstract

A set of output utility functions is described that allows the programmer to direct output to four different output devices (array, file, printer, and terminal) in a device-independent manner. These output functions provide the programmer with the ability to switch output devices without recoding application programs, and the ability to control particular device characteristics. The functions include logic for line counting and (optional) page headings, and are easy to learn and use. Technical notes, examples, function listings, and a discussion of potential extensions are also included. These output functions may usefully be included in the utility library of every micro and mainframe APL installation.