Introduction

Most languages store programs and data separately. APL is unusual in that it allows you to store programs and data together in a workspace.

This can be inefficient if your dataset gets very large; when your workspace is loaded, you are loading ALL of your data, whether you need it or not.

It also makes it difficult for other users to access your data, particularly if you want them to be able to update it.

In these circumstances, you must extract your data from your workspace, and write it to a file on disk, thus separating your data from your program. There are many different kinds of file format. This section is concerned with the APL Component File system which preserves the idea that your data consists of APL objects; hence you can only access this type of file from within APL

The Component File system has a set of system functions through which you access the file. Although this means that you have to learn a whole new set of functions in order to use files, you will find that they provide you with a very powerful mechanism to control access to your data.