I think he means

symmetricDifference a b = (a `union` b) `difference` (a `intersection` b)

Or equivalently

symmetricDifference a b = (a `difference` b) `union` (b `difference` a)

Basically the elements in one of the two sets but not both. He's claiming a direct function would be faster than combining three.

Note that (a `difference` b \= b `difference` a) but (a `symmetricDifference` b == b `symmetricDifference` a).

On Sun, Jun 21, 2015 at 3:15 PM, Ruben Astudillo <ruben.astud@gmail.com> wrote:

On 20/06/15 21:49, Zemyla wrote:

Alternatively, could we get a merge interface for Set and IntSet roughly
matching Map and IntMap?

Could you expand on what you mean? I understand it as that having operations of
(Int)Map for (Int)Set, why don't just use (Int)Map then?
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