No Excel? It's the most widely used visual, grid based functional programming environment. MS claim more than a billion Office users. Any time one of them edits a formula in Excel they're programming. Would also be nice to see AVS/Express in there. Jeff Vroom built the AVS VPE more than 20 years ago.
Not only is Excel functional programming, it's lazy, pure functional programming: each cell (variable) can only define itself, and so cannot change the content of other cells. Evaluation is controlled by the Excel runtime system, which doesn't evaluate cell expressions unless they're scrolled into view, or needed to evaluate a cell that's scrolled into view.
Exactly like Haskell. If Excel were impure, it would mean an expression in one cell would have the power to alter the value of another cell. So, in effect, a cell becomes a synonym for the expression it contains, rather than a -- possibly mutable -- reference to the value its expression evaluates to.
Huh; never heart about this! Is there a good walkthrough of this functionality for people who already work with relational databases and just want a compare-and-contrast?
True. Excel makes a distinction between functions and commands. Functions can't modify other cells, commands can. Since VBA can be used for "automation" (invoking UI events) it can modify cells.
I think she raises especially important points when she mentions that Excel is used everywhere, that it suffers from all the technical debt problems that regular software development suffers from, and that buggy Excel sheets have big consequences (the austerity paper bug comes to mind[0]). So even if "real" programmers don't want to program in it, it still should be taken seriously given its place in the world.
