symmetricDifference :: Set a -> Set a -> (Set a, Set a, Set a)
Since projections from a 3-tuples are not in base (why?, one could wonder), I plea for a telling result name that helps confusing these three outputs. Something like data SymmetricDifference = SymmetricDifference { symDiffLeft :: Set a , symDiffCommon :: Set a , symDiffRight :: Set a } (Also fixing the problem of absent projections.) On 2020-12-01 10:16, Ben Franksen wrote:
Would it make sense to add a function like the following to containers:
symmetricDifference :: Set a -> Set a -> (Set a, Set a, Set a) symmetricDifference a b = (a \\ b, a `intersection` b, b \\ a)
with the idea that this can be implemented more efficiently as a primitive than the above specification? (And similarly for HashSet.)
If this is the case, then perhaps difference and intersection could be defined in terms of this new primitive:
difference a b = let (r, _, _) = symmetricDifference in r intersection a b = let (_, r, _) = symmetricDifference in r
*if* it turns out that this does not degrade performance.
Cheers Ben
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