Created
October 31, 2012 05:23
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Symmetric set difference in Haskell
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module Example ( | |
(∆) | |
) where | |
unique :: (Eq a) => [a] -> [a] | |
unique [] = [] | |
unique (x:xs) = x:(unique (filter (/= x) xs)) | |
without :: (Eq a) => [a] -> [a] -> [a] | |
xs `without` ys = [ x | x <- xs, not (x `elem` ys)] | |
(∆) :: (Eq a) => [a] -> [a] -> [a] | |
(∆) xs ys = | |
let uniqueXs = unique xs | |
uniqueYs = unique ys | |
in (uniqueXs `without` uniqueYs) ++ (uniqueYs `without` uniqueXs) | |
main :: IO () | |
main = print $ [1, 2, 3, 4, 5] ∆ [3, 4, 5, 6, 7] |
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