A critic of Guido's blog on Python's lambda

[Thomas F. Burdick]

Ken Tilton <kentilton at gmail.com> writes:

> No, you do not want on-change handlers propagating data to other
> slots, though that is a sound albeit primitive way of improving
> self-consistency of data in big apps. The productivity win with
> VisiCalc was that one simply writes rules that use other cells, and
> the system keeps track of what to update as any cell changes for
> you. You have that exactly backwards: every slot has to know what
> other slots to update. Ick.

No no, that's fine and the way it should be: when you change a slot,
it should know who to update.  And that's also the way it works in
Cells.  The trick is that Cells takes care of that part for you: all
the *programmer* has to care about is what values a slot depends on --
Cells takes care of inverting that for you, which is important because
that's a job that a computer is much better at than a human.