User Interfaces for Live Programming

Live programming has attracted much attention for eliminating the gulf between code and execution. To design live programming systems, we first need to understand what we are developing. Once we gain domain-specific knowledge of the target applications, we create user interfaces to edit the running application, such as scrubbing sliders, color palettes, and timeline interfaces. The key to the fluid programming experience of live programming is the combination of deep understanding of the target applications and adoption of interactive user interfaces.

In the keynote talk at LIVE '17, I discussed the liveness of programming systems in light of user interface design. I introduced user interfaces for programming and discussed the importance of integrating graphical representations into programming environments. I extended the scope of "liveness" by describing two kinds of interactions, physical and developer-user, and provided insights on designing future live programming systems.

In particular, regarding the user interfaces for enhancing developer-user interactions, there are two sub-projects called Live Tuning and User-Generated Variables.

Live Programming systems provide concrete information about how the program behaves when it is executed. With help of this concrete information, programmers can easily iterate on editing and testing the program behavior.

Please note that the origin of Live Programming is not new as you can see early examples in visual programming and object-oriented programming environments. Then, why is it attracting much attention these days? In short, I consider it is because of its focus on the user experience.

From now on, I will discuss three perspectives on user interface design of Live Programming systems.

Programming with End-users

As Live Programming systems provide interactive and intuitive user interfaces for debugging and editing programs, some of the user interfaces can be exposed to the end-users so that they can customize the programs as they wish. [Live Tuning]

When the provided user interfaces cannot satisfy their needs, they can still submit requests to programmers with rich contextual information provided by the Live Programming systems. [User-Generated Variables]

Programming this Material World

Live Programming often targets simple applications such as drawing graphics. In contrast, "software is eating the world" and there are interesting applications such as physical computing and virtual reality.

Their actual "framerate" can be very slow; e.g. printing device enclosures and producing scent. Emulating, or sometimes even pretending, is needed to provide the continuous feedback. Making full use of five senses in programming environments would be crucial in the near future.

Programming with Time Travel

Live Programming puts focus on providing live feedback to the programmer, but it does not always mean providing realtime information of the running program.

The timeline interface and record and replay features together provide time traveling experience and play an important role to find critical timings in the history. Once the timing of interest is found, editing the code and program input would update the program output, allowing the programmer to explore future"s."

The following projects are highly relevant to the topic.