> So I think the needs aren't for good print strings.  The needs are  
> actually for much higher-level tools that allow one to
> - compare object graphs with a richer result than merely equal or  
> not, i.e. explore the comparison
> - trace the evolution of object graphs during computation, ideally  
> supporting evolution in lock-step of more than one graph, perhaps  
> simply allowing one to record the sequence of evolutions such that  
> one can compare one trace to another
>
> How general is this kind of thing?  Do others find themselves  
> looking at this kind of thing often?  I fear not.