I think on the numworks you can use the arrow keys to pull up an old expression. I think it would be really cool if someone built out an interpreted, nicely rendered calculator language/repl that could do variables and stuff. Might be an interesting idea
>>varun_+(OP)
You can, but it seems to just select & use the results of previous expressions. I often want to modify & iterate on the formulas I've previously entered. Or rerun them.
I think there was a calculator like this about a decade ago released for macos, but I can't remember what it was called. Brilliant little piece of software. I assume most people didn't understand it, and it slowly disappeared.