[R] Excel (off-topic, sort of)

[Alberto Monteiro]

Chris wrote:
>
> Typically, people in the R community are not used to the spreadsheet 
> paradigm and need some time to be able to take advantage of 
> automatic recalculation, (...)
>
Do you know what's in my wish list?

I wish spreadsheets and computer languages had gone one
step further.

I mean, it's nice to define Cell X to be "equal" to
Cell Y + 10, and then when we change Cell Y, magically we
see Cell X change.

But why can't it be the reverse? Why can't I change Cell X
_and see the change in Cell Y_?

Maybe I'll write a letter to Santa Claus [there are people
who write to congressman; they must have more faith than me].
I wish a language where I can write

  a = b + 10

and then when I write

  a = 20

the language automatically assigns b = 10.

There's a way to simulate this in any computer language, or even
in Excel: instead of "variables" or "cells", we have structures
with value and a flag. The flag dictates if it's input, undefined
or calculated. And then there's a list of relations. So the
program/language/spreadsheed loops through the list of relations,
detects whenever we can infer a new calculated value, and calculates
it, until there's nothing else to do or a contradiction is found.

Alberto Monteiro