ATOL

Abstract

The use of complex data structures in most common languages is often unnecessarily confusing to all but the most experienced programmers. ATOL has been designed to include a variety of data structures in a way that is both simple to understand and easy to handle, yet sufficiently general and powerful for a wide range of applications. The syntax of the language is quite simple and suitable for interactive program development at on-line terminals, rather like Basic.The primary data type of the language is a character string or text. Three classes of data structures may be constructed: records, files and sequences. For each of these, the components may be either texts or other structures in any of the three classes. Records may be defined recursively to generate lists or trees of variable size. Arrays are not present in the language, their place being taken by files which are structures containing variable numbers of components selected by text keys. Data from a very wide range of applications may thus be easily and conveniently represented.The method used to denote the components of a structure in a program is significantly simpler than that used in languages like Algol 68 and Pascal. In addition, the need to use pointers explicitly has been kept to a minimum, thus reducing another source of confusion among inexperienced programmers. In general the language has been designed for the beginning programmer whose interests are in non-numerical applications such as occur in the arts and humanities and many areas of commercial data processing.