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-rw-r--r--src/Erebos/Storage/Merge.hs7
1 files changed, 5 insertions, 2 deletions
diff --git a/src/Erebos/Storage/Merge.hs b/src/Erebos/Storage/Merge.hs
index 9d9db13..a3b0fd7 100644
--- a/src/Erebos/Storage/Merge.hs
+++ b/src/Erebos/Storage/Merge.hs
@@ -97,13 +97,16 @@ storedGeneration x =
doLookup x
+-- |Returns list of sets starting with the set of given objects and
+-- intcrementally adding parents.
generations :: Storable a => [Stored a] -> [Set (Stored a)]
generations = unfoldr gen . (,S.empty)
- where gen (hs, cur) = case filter (`S.notMember` cur) $ previous =<< hs of
+ where gen (hs, cur) = case filter (`S.notMember` cur) hs of
[] -> Nothing
added -> let next = foldr S.insert cur added
- in Just (next, (added, next))
+ in Just (next, (previous =<< added, next))
+-- |Returns set containing all given objects and their ancestors
ancestors :: Storable a => [Stored a] -> Set (Stored a)
ancestors = last . (S.empty:) . generations