How to Tame an Unpredictable Emergence? Design Strategies for a Live-Programming System

Programming environments that provide a feeling of liveness help professionals and amateurs alike to approach unfamiliar domains with ease through short feedback loops. Exploration and experimentation are promoted because any change to the program under construction can be observed immediately. However, live-programming systems such as Squeak/Smalltalk struggle with the predictable emergence of adapted program behavior as object communication can be unconstrained and diverse. While programmers wish for immediate effects, it would be helpful to at least know whether anything will happen after some time. In this chapter, we take a closer look at the means available in Squeak to explore and adjust object state and object behavior so that programmers can ensure the system’s responsiveness and hence observe gradual or even induce eventual emergence. We argue that these design strategies are sufficient to architect communication patterns that reward changes with immediate effects. We believe that our work can help programmers to better understand their leverage toward a predictable emergence in systems whose liveness stems from objects and messaging in a space where tools and applications live side by side.