Pagebreaks: Multi-Cell Scopes in Computational Notebooks

Figure 1: A Pagebreak is a language construct for adding a scope around multiple Jupyter Notebook cells. Left: A notebook using Pagebreaks. A Variables defined within the indented cells can only be used within a defined portion of the notebook. Unlike defining the same variables inside a function, the Pagebreak does not interfere with key exploratory interactions, such as B: interleaving code and its output, C: using cells as impromptu versions, and D: iteratively composing programs with single-line cells. E: Only variables exported at the bottom of a Pagebreak are available for other cells. For example mean_ratings is available in the bottom Pagebreak, but ratings_by_title is not. Right: In contrast, functions provide scopes at the cost of these exploratory interactions. F: Functions prevent iterative composition or using cells as impromptu versions inside a function body. G: Functions prevent interleaving code and output; instead all printed output from a function appears together at the call site, not interleaved with the function body. Example adapted from [30].