A functional programming approach for macro development

Developing macro queries in software systems is a complex task for many users. Geographical information systems (GIS) are large software systems that require much effort to develop expertise in. A functional programming design approach has a number of distinct strengths that can be represented in a graphical query language interface to aid users in macro query development. A visual functional query language (VFQL) for Geographical Information Systems is presented and its strengths and weaknesses discussed. The system is based on a visual functional programming design approach. This offers a consistent, non‐procedural, strongly typed environment where users can develop their own higher order functions. The approach integrates functional programming, visual programming and knowledge and rules. VFQL’s effectiveness is evaluated compared with a text based command language for GIS macro query development. The results of an experiment indicate that users could develop solutions to simpler tasks more quickly and with fewer errors than a comparative text based command language. On more complex tasks there was no significant difference. From this we deduce that VFQL demonstrates certain design features to help the development of macros or small programs for users but that the complexity of the problem in difficult tasks is likely to be the most important determinant of the error rate and time to complete the task.