> But the changes I'd need in this case are reaching too far.

Indeed :)

> They'd include:
> - Upper bounds of integer intervals are exclusive and lower bounds  
> inclusive
> - Index ranges start at zero
> - The positions of Positionable Streams would take the same values as
>   the indexed variables of their underlying collections.
>
> With theses changes predicates involving indexes and positions get  
> more elegant.
> This in turn lessens the burden you face when formulating  
> specifications of
> methods and reasoning about methods to prove that they meet the  
> specification.
>
> This in turn is the only technique I know of that saves you from  
> "off by one"
> errors in particular and "bugs" in general.
>
> So the changes *are* important.
>
> And hard to implement in Smalltalk.

Indeed.

> Or, viewed as biological species, Squeak and even Smalltalk-80  
> evolved to a
> level where they lost the flexibility to meet the "new" challenge  
> of switching
> from the dark art of medieval metaphors to the scientific technique  
> of logical
> reasoning.

This is clear that I was thinking about gemstone possibility of  
having multiple
versions at the same time as a way to support a muc smoother evolution.

Stef