[jklp]

Agree about the "just type in text" paradigm though I feel they suffer from the "empty state" problem. You can see I tried to mitigate with the "blank sheet" placeholder text, and on web there're templates available. Unfortunately it appears only a fraction of users use the templates, and of course users never read the placeholder text!

I haven't heard of immediate / retained mode before - interesting concept! Figr is more straight forward and evaluates a line as "0" if there's an error (the opposite of "be conservative in what you send, be liberal in what you accept"!) so they are problems where entire calculations are "wiped out" if there's an error on a line, but I think that's the trade of to having accurate results.

As for a custom text view completely agree! I did do that initially though switched over to draftjs later and (despite it's lack of good guides) has been a huge time saver!

[avdlinde]

How about using something like NaN instead of 0? To not have a small set of calculations being all 0 and missing from a larger end result (which would go to NaN instead).

[alsajjad]

Nice!