Range proposal

[Manfred_Nowak]

Bill Baxter wrote:

> think of a range more as an iterator plus a sentinel

The problem with both models is, that there are canonical operators one 
both models, which are somehow frantically hidden. This is shown

1) by the deliberately constructed compound of `[left,right]
[Diff,Union]'
2) the missing definition of a "subrange"

Both seem undefinable without having some notion of "concatenation"---
and if one has concatenation, a request for the reverse operation 
"splitting" is unavoidable.

In fact the semantics of `r.moveTo(s)' seems not to be fully defined in 
both approaches.

In fact in your approach of thinking of `r.moveto(s)', the "iterator" 
of `s' turns into a "sentinel" for `r', thereby making sentinels and 
iterators to synonyms.

If there is indeed a structural similarity to Andrei's approach, the 
same problem must show up somewhere.

-manfred 


-- 
If life is going to exist in this Universe, then the one thing it 
cannot afford to have is a sense of proportion. (Douglas Adams)