## Dataflow calculators

### July 7, 2006

Google spreadsheets lacks some of the “what-if analysis” features of Excel, particulary goal seek and scenarios. That’s ok, of course, because most people use spreadsheets to maintain simple tables and perform simple calculations. Excel is overkill for most people. Instead, I think people might prefer a dataflow calculator, where calculations are performed immediately. Perhaps ZigZag is similar; maybe Subtext, too. Basically, you write out normal program code: “weight=160; height=72; bmi= (weight/height^2)*703”. But like a spreadsheet, the equation is replaced by the answer: 21.70. Maybe the ‘bmi’ variable would have a ‘F’ subscript to indicate it’s a function. Now any change to the height or weight variables immediately changes the BMI. I’m not sure what to do with recursive equations. You don’t want people writing loops. Sometimes you can get away with lazy evaluation, or someone might seed it with initial data: “if n=0, fib = 1”. I’ll need to think about that.