1 files changed, 37 insertions, 0 deletions
diff --git a/src/Erebos/Util.hs b/src/Erebos/Util.hs
new file mode 100644
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+++ b/src/Erebos/Util.hs
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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