Timeline Adding the Time Dimension to Spreadsheets

Tomas Petricek, Tomáš Boďa

In Proceedings of OOPSLA 2026

Spreadsheets make it easy to express computations over two-dimensional data, but two dimensions are not enough to express rich computations involving time such as physics simulations, agent-based modelling, financial data analyses, or simple interactive applications.

We present Timeline, a system that adds discrete time to spreadsheets. We motivate the design of Timeline through a small-scale formative study, present a core calculus that models system runtime, use it to formalise a static analysis to determine the required number of past values, and evaluate the system using a series of case studies from the four aforementioned areas.

The paper also shows that a large number of advanced programming language concepts can be directly applied in the context of spreadsheets with time. Timeline draws from dataflow languages to express computations over time, coeffect systems to ensure bounded memory usage, functional reactive programming to support interactivity, and grammars of graphics to support composable visualizations.

Paper and more information

• Download the paper (PDF)
• Check out the Timeline project homepage
• Live demo: Planetary orbit simulation
• Live demo: Flocking simulation
• Live demo: Moving average crossover
• Live demo: Flappy Bird clone

Teaser figure

Bibtex

If you want to cite the paper, you can use the following BibTeX information.

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@article{petricek-2026-timeline,
  author    = {Tomas Petricek and Tomáš Boďa},
  title     = {Timeline: Adding the Time Dimension to Spreadsheets},
  journal   = {Proc. {ACM} Program. Lang.},
  volume    = {10},
  number    = {{OOPSLA2}},
  articleno = {370},
  year      = {2026},
  doi       = {10.1145/3839502}
}

If you have any comments, suggestions or related ideas, I'll be happy to hear from you! Send me an email at tomas@tomasp.net or get in touch via BlueSky at @tomasp.net.