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module Erebos.Util where
uniq :: Eq a => [a] -> [a]
uniq (x:y:xs) | x == y = uniq (x:xs)
| otherwise = x : uniq (y:xs)
uniq xs = xs
mergeBy :: (a -> a -> Ordering) -> [a] -> [a] -> [a]
mergeBy cmp (x : xs) (y : ys) = case cmp x y of
LT -> x : mergeBy cmp xs (y : ys)
EQ -> x : y : mergeBy cmp xs ys
GT -> y : mergeBy cmp (x : xs) ys
mergeBy _ xs [] = xs
mergeBy _ [] ys = ys
mergeUniqBy :: (a -> a -> Ordering) -> [a] -> [a] -> [a]
mergeUniqBy cmp (x : xs) (y : ys) = case cmp x y of
LT -> x : mergeBy cmp xs (y : ys)
EQ -> x : mergeBy cmp xs ys
GT -> y : mergeBy cmp (x : xs) ys
mergeUniqBy _ xs [] = xs
mergeUniqBy _ [] ys = ys
mergeUniq :: Ord a => [a] -> [a] -> [a]
mergeUniq = mergeUniqBy compare
diffSorted :: Ord a => [a] -> [a] -> [a]
diffSorted (x:xs) (y:ys) | x < y = x : diffSorted xs (y:ys)
| x > y = diffSorted (x:xs) ys
| otherwise = diffSorted xs (y:ys)
diffSorted xs _ = xs
intersectsSorted :: Ord a => [a] -> [a] -> Bool
intersectsSorted (x:xs) (y:ys) | x < y = intersectsSorted xs (y:ys)
| x > y = intersectsSorted (x:xs) ys
| otherwise = True
intersectsSorted _ _ = False
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