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.