Upstreaming `ord_lookup`, `ord_range` and `rb_visit_range`

[kwon-young]

@jan

Did you check for current practice on any of these? If that exists we must consider aligning as first option.

I couldn’t find anything in other prolog implementation yet.
I found this earlier discussion: Selecting a range in a dictionary
which shows that at least rb_visit_range might be more broadly useful than just myself.

N.B.: Sicstus prolog has a predicate called avl_range but the equivalent is rb_values

@jan

It is a little unclear where that should go. library(ordsets) is not about pairs. library(pairs) could be better.

Yes, I’m confused too as to where ord_lookup should go.
I would slightly favor putting in ordsets as the predicate only advantage over member(K-V, L), K == MyKey is that the list of pairs is sorted, meaning we can unroll the search.