Documenting Spreadsheets with Pseudo-Code: an Exercise with Cash-Flow and Loans

“Look before you leap”; “a stitch in time saves nine”; “more haste, less speed”. Many proverbs declare the wisdom of planning before doing. We suggest how to apply this to Excel, by explaining and specifying spreadsheets before coding them, so there will always be documentation for auditors and maintenance programmers. The specification method uses “pseudo-code”: code that, for precision and conciseness, resembles a programming language, but is not executable. It is, however, based on the notation used by our Excelsior spreadsheet generator, which is executable. This paper is structured as a tutorial, in which we develop a simple cash-flow and loans spreadsheet.

💡 Research Summary

The paper presents a disciplined approach to building Excel‑based financial models by first writing a formal, yet non‑executable, specification in pseudo‑code. The authors argue that, just as software developers write design documents before coding, spreadsheet creators should do the same to ensure transparency, auditability, and ease of maintenance. Their method hinges on a pseudo‑code language that mirrors conventional programming syntax—variables, tables, loops, conditionals, and assertions—while remaining readable to non‑programmers.

The tutorial begins with a simple cash‑flow model. The authors define the fundamental parameters (initial cash, period, income, expense) and declare a table `CashFlow