On 2015-03-05 at 23:59:23 +0100, David Feuer wrote:
There are a few rather conspicuously missing features:
[...]
2. A way to insert an element if an == one is not already present (insert replaces an existing one with a new one). Currently, as far as I can tell, this can only be done using either
if e `member` s then s else insert e s which potentially descends the tree twice for no reason
or
s `union` singleton e
which is documented as being O(|s|+1), although I wouldn't be shocked if the documentation were too pessimistic in this case.
3. A way to delete an element and simultaneously find out whether it was in the set.
Maybe (2) and (3) can be combined, c.f. https://github.com/gregorycollins/hashtables/issues/6#issuecomment-37523794 there's related tickets in unordered-containers too: https://github.com/tibbe/unordered-containers/issues/93 (even though those are for associative arrays, it'd be good if we could come up with a coherent story for these operations rather than ending up with subtly differently named/typed operations -- assuming it makes sense to find a uniform scheme) Cheers, hvr