Lowering the Barriers to Successful Programming

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

Although computer programming has existed in its modern form for half a century, it remains accessible only to a small fraction of the population. While programming is an inherently difficult activity, there are currently many barriers that prevent large portions of the population from learning to program a computer. Some of these barriers can be overcome through new facilities in programming environments. Current advanced programming environments provide a number of tools to help programmers construct programs: direct manipulation facilities to set up user interface widgets, code editors with coloring and indenting, and various pop-up menus that help construct code. However, there is little support to help users write the code that handles the dynamic responses to events and high-level behaviors. Furthermore, the tools for debugging code when something goes wrong are not much different than what has been available for 60 years: print statements, break-points and inspecting the values of variables. This is in spite of the fact that research shows that debugging and specifying the dynamic behavior of code are some of the most difficult aspects of programming. In this project, Alice, a programming environment that makes it very easy to program interactive 3D graphics, will be augmented to provide significantly better tools to help both novice and expert programmers develop and debug their programs. A number of novel ideas that have not yet appeared in any system will be implemented, along with the best ideas from prior systems and research (which have never been combined into one system). Thorough formative and summative user testing of the ideas will provide an understanding of which of the features are most useful; this will guide further refinement of Alice so it does the best possible job of guiding programmers to create correctly working solutions. In addition to addressing the mechanical issues of programming, Alice provides an opportunity to address the fact that relatively few women learn to program, which can be called a sociological barrier. Many girls turn away from science and technology during their middle school years, usually never to return. Middle school girls represent a particularly difficult challenge, requiring a highly motivating system with tremendous mechanical support. The PIs' approach to lowering the social barriers is to provide programming as a means to other motivating ends, especially storytelling. The intellectual merit of the proposed research will be to discover new techniques to aide in the construction and debugging of programs, and to measure and validate the impact and effectiveness of these techniques with both novice and expert programmers. The techniques envisioned to help with code creation include: graphical and textual editors for storyboards that will help transition story ideas into code; demonstrational and direct manipulation techniques for specifying dynamic behaviors; check-pointing and undo facilities so programmers can more easily explore multiple solutions and backtrack to a known state when necessary; smart copy-and-paste that will help in transforming and reusing code; support for collaboration and sharing of code; tools that will suggest likely causes and fixes for run-time errors; and embedded special-purpose editors to help construct Boolean expressions and scientific formulas. Techniques to support understanding, testing and debugging include: providing easy inspection of data so programmers can tell what is happening; pausing or break-pointing on any program event including objects that are being changed, created, or deleted; changing values at run time to explore the effects; providing a time-line visualization to show important events and enabling programs to run forwards and backwards from any point; support for asking "why" questions that will tie graphics and program events to the code that caused them; support for asking "why not" questions, which will use heuristics to propose reasons why some event did not happen; and search capabilities so programmers can find variables with particular values, or objects with certain properties. Broader Impacts: The broader impacts resulting from this research will be to help make programming more accessible to novice programmers, and more effective for both novice and expert programmers. One important target group will be middle school boys and girls who are not necessarily motivated to learn programming. The PIs believe they can make programming accessible and compelling to this audience, while at the same time making it easier for experienced programmers. These benefits will be evaluated using thorough user tests at all points of the design and implementation.