The aim of this paper is to point out a remarkable similarity between a range of interactive programming systems. In many programming systems, the user can interactively construct a program by repeatedly triggering a completion mechanism and choosing one of the options. This is the case with code editors for object-oriented languages (choosing a member), data exploration environments (choosing a transformation), but also theorem provers (choosing a tactic) and structure editors (choosing a grammar rule).

We capture the essence of this interaction pattern through a small formal model called the choose-your-own-adventure calculus. We show that a wide range of systems fits the model, but also uncover subtle differences between the instances. To make the differences precise, we characterise basic properties of choose-your-own-adventure systems, including correctness, completeness and uniqueness. We also show how the calculus enables the study of advanced interaction patterns including mixed-initiative interaction, AI-based programming assistants and programming by demonstration.

We strongly believe that interaction with programming systems deserves as much attention as the underlying programming languages. Our work is one step in this direction. It provides a way of talking about commonalities and subtle differences between multiple interactive programming systems and enables a transfer of ideas between interactive systems from very different domains.