RE: Unit validation in spreadsheets

["Paul A. Steckler" <steck stecksoft com>]

> Does this transformer/validator have to be created per 
> function (for all functions?).

Yes.

> Isn't there a more minimalist 
> approach available - for example, adding and subtracting need 
> to take the same units, whatever they are. Multiplication and 
> division can take any unit. Other functions might not care 
> about units.

That's exactly what the transformers enforce.
So you specify the transformers for addition and 
subtraction as

 + :: u,u -> u
 - :: u,u -> u 

That wasn't much work, right? :-)