Set.prototype.entries: indices as keys?

[Axel Rauschmayer]

> Sets are not a linear data structure, so the order of entries in a Set is irrelevant, unlike an Array whose elements must have an explicit position. Set entries in JS have an iteration order purely to match programmer intuition (and ensure that all implementations adhere), however there is no structural importance of the order. 

You can impose an order on the elements of a set, though. For example, Java’s `SortedSet` [1] has the methods `first()` and `last()`, which are occasionally useful. I agree that it feels weird to have indices attached to set elements, but it would at least make `entries()` useful. You could iterate and treat the first element and/or the last element differently. But the same can be achieved by iterating over a `zip()` of a set and a `range()` (assuming iterable-based tool functions `zip` and `range`).

[1] http://docs.oracle.com/javase/7/docs/api/java/util/SortedSet.html

-- 
Dr. Axel Rauschmayer
axel at rauschma.de
rauschma.de