Posts about MAP.
REDUCE is the most powerful of the functional array functions and the most overlooked. The lambda which means you can accumulate strings, and replace calculations that used to need VBA.
LAMBDA, MAP, REDUCE, SCAN, BYROW. These are functional programming primitives. Excel is shipping them one by one, and most users are still writing nested IFs. The spreadsheet you learned in 2015 has been quietly replaced by something much more powerful.
You'll build a dropdown list that reads from a structured table and includes every new row automatically. No named range maintenance, no 'why isn't my new entry showing up' moments. Structured table plus a spill reference, and your validation list never needs touching again.
MAP takes your LAMBDA and runs it on every element in an array. No helper columns, no dragging formulas, no VBA loops. It's the Excel equivalent of a functional programming pattern, and once you've used it, going back to column-by-column formulas feels like a step backwards.