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thomas-mcdonald/union.hs

Created January 13, 2013 21:09
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union lol
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union.hs
union [] [] = []
union [] ys = ys
union xs [] = xs
union (x@(n,_):xs) ys
| has n ys = (join x (find n ys)):(union xs (without n ys))
| otherwise = x:(union xs ys)
where
find p = filter (\x -> fst x == p)
without p = filter (\x -> fst x != p)
has p = length (find p) != 0
join (n,x) (_,y) = (n,x+y)
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