See What You Need: Helping End-users to Build Abstractions

Abstract

It has been argued that most end-users would not want to write programs, no matter what kind of tools they had to help them. This paper analyzes the reasons for that situation, and addresses them with a new approach to programming. There is a large class of users who are very reluctant to create any kind of abstraction within a computer (they will not create a new directory, let alone a Word macro). But these people do create abstractions in their everyday lives outside the computer. The reason for their computer habits can be explained in terms of a simple investment and risk model. See What You Need (SWYN) is a system intended to deliver the capabilities—not just of Word macros, but of Perl—to end-users. The techniques it adopts are those of programming by example, visual program representation and direct manipulation. SWYN is not intended to be a complete system, and is unlikely to develop into a complete Perl replacement. It is a research vehicle, supporting the evaluation of specific features aimed at reducing the perceived risk of abstraction in programming. This paper describes two elements of the SWYN project, both of them related to the regular expressions that are central to pattern matching in Perl. The first is a prototype system that acquires regular expressions from the type of examples required in direct manipulation of data for programming. The second is an experimental evaluation of alternative notations for visualizing regular expressions. This experiment demonstrated a clear advantage for graphical notations in typical end-user tasks, both over conventional regular expressions, and over a tutorial-style textual notation. The overall effect is a reduction both in programming investment and in perceived risk.