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Exact lookup

1. LookupRequest :: Maybe Text -> Maybe [Key] -> Maybe PropertyMask -> Maybe ReadOptions -> LookupRequest

   gogol-datastore	Gogol.Datastore.Types

   No documentation available.

2. data LookupResponse

   gogol-datastore	Gogol.Datastore.Types

   The response for Datastore.Lookup. See: newLookupResponse smart constructor.

3. LookupResponse :: Maybe [Key] -> Maybe [EntityResult] -> Maybe [EntityResult] -> Maybe DateTime -> Maybe Base64 -> LookupResponse

   gogol-datastore	Gogol.Datastore.Types

   No documentation available.

4. unsafeLookupStaticPtr :: StaticKey -> IO (Maybe (StaticPtr a))

   base	GHC.StaticPtr

   Looks up a StaticPtr by its StaticKey. If the StaticPtr is not found returns Nothing. This function is unsafe because the program behavior is undefined if the type of the returned StaticPtr does not match the expected one.

5. insertLookupWithKey :: (Key -> a -> a -> a) -> Key -> a -> IntMap a -> (Maybe a, IntMap a)

   containers	Data.IntMap.Internal

   The expression (insertLookupWithKey f k x map) is a pair where the first element is equal to (lookup k map) and the second element equal to (insertWithKey f k x map).

   let f key new_value old_value = (show key) ++ ":" ++ new_value ++ "|" ++ old_value
   insertLookupWithKey f 5 "xxx" (fromList [(5,"a"), (3,"b")]) == (Just "a", fromList [(3, "b"), (5, "5:xxx|a")])
   insertLookupWithKey f 7 "xxx" (fromList [(5,"a"), (3,"b")]) == (Nothing,  fromList [(3, "b"), (5, "a"), (7, "xxx")])
   insertLookupWithKey f 5 "xxx" empty                         == (Nothing,  singleton 5 "xxx")
   

   This is how to define insertLookup using insertLookupWithKey:

   let insertLookup kx x t = insertLookupWithKey (\_ a _ -> a) kx x t
   insertLookup 5 "x" (fromList [(5,"a"), (3,"b")]) == (Just "a", fromList [(3, "b"), (5, "x")])
   insertLookup 7 "x" (fromList [(5,"a"), (3,"b")]) == (Nothing,  fromList [(3, "b"), (5, "a"), (7, "x")])
   

   Also see the performance note on fromListWith.

6. splitLookup :: Key -> IntMap a -> (IntMap a, Maybe a, IntMap a)

   containers	Data.IntMap.Internal

   Performs a split but also returns whether the pivot key was found in the original map.

   splitLookup 2 (fromList [(5,"a"), (3,"b")]) == (empty, Nothing, fromList [(3,"b"), (5,"a")])
   splitLookup 3 (fromList [(5,"a"), (3,"b")]) == (empty, Just "b", singleton 5 "a")
   splitLookup 4 (fromList [(5,"a"), (3,"b")]) == (singleton 3 "b", Nothing, singleton 5 "a")
   splitLookup 5 (fromList [(5,"a"), (3,"b")]) == (singleton 3 "b", Just "a", empty)
   splitLookup 6 (fromList [(5,"a"), (3,"b")]) == (fromList [(3,"b"), (5,"a")], Nothing, empty)
   

7. updateLookupWithKey :: (Key -> a -> Maybe a) -> Key -> IntMap a -> (Maybe a, IntMap a)

   containers	Data.IntMap.Internal

   Lookup and update. The function returns original value, if it is updated. This is different behavior than updateLookupWithKey. Returns the original key value if the map entry is deleted.

   let f k x = if x == "a" then Just ((show k) ++ ":new a") else Nothing
   updateLookupWithKey f 5 (fromList [(5,"a"), (3,"b")]) == (Just "a", fromList [(3, "b"), (5, "5:new a")])
   updateLookupWithKey f 7 (fromList [(5,"a"), (3,"b")]) == (Nothing,  fromList [(3, "b"), (5, "a")])
   updateLookupWithKey f 3 (fromList [(5,"a"), (3,"b")]) == (Just "b", singleton 5 "a")
   

8. insertLookupWithKey :: (Key -> a -> a -> a) -> Key -> a -> IntMap a -> (Maybe a, IntMap a)

   containers	Data.IntMap.Lazy

   The expression (insertLookupWithKey f k x map) is a pair where the first element is equal to (lookup k map) and the second element equal to (insertWithKey f k x map).

   let f key new_value old_value = (show key) ++ ":" ++ new_value ++ "|" ++ old_value
   insertLookupWithKey f 5 "xxx" (fromList [(5,"a"), (3,"b")]) == (Just "a", fromList [(3, "b"), (5, "5:xxx|a")])
   insertLookupWithKey f 7 "xxx" (fromList [(5,"a"), (3,"b")]) == (Nothing,  fromList [(3, "b"), (5, "a"), (7, "xxx")])
   insertLookupWithKey f 5 "xxx" empty                         == (Nothing,  singleton 5 "xxx")
   

   This is how to define insertLookup using insertLookupWithKey:

   let insertLookup kx x t = insertLookupWithKey (\_ a _ -> a) kx x t
   insertLookup 5 "x" (fromList [(5,"a"), (3,"b")]) == (Just "a", fromList [(3, "b"), (5, "x")])
   insertLookup 7 "x" (fromList [(5,"a"), (3,"b")]) == (Nothing,  fromList [(3, "b"), (5, "a"), (7, "x")])
   

   Also see the performance note on fromListWith.

9. splitLookup :: Key -> IntMap a -> (IntMap a, Maybe a, IntMap a)

   containers	Data.IntMap.Lazy

   Performs a split but also returns whether the pivot key was found in the original map.

   splitLookup 2 (fromList [(5,"a"), (3,"b")]) == (empty, Nothing, fromList [(3,"b"), (5,"a")])
   splitLookup 3 (fromList [(5,"a"), (3,"b")]) == (empty, Just "b", singleton 5 "a")
   splitLookup 4 (fromList [(5,"a"), (3,"b")]) == (singleton 3 "b", Nothing, singleton 5 "a")
   splitLookup 5 (fromList [(5,"a"), (3,"b")]) == (singleton 3 "b", Just "a", empty)
   splitLookup 6 (fromList [(5,"a"), (3,"b")]) == (fromList [(3,"b"), (5,"a")], Nothing, empty)
   

10. updateLookupWithKey :: (Key -> a -> Maybe a) -> Key -> IntMap a -> (Maybe a, IntMap a)

    containers	Data.IntMap.Lazy

    Lookup and update. The function returns original value, if it is updated. This is different behavior than updateLookupWithKey. Returns the original key value if the map entry is deleted.

    let f k x = if x == "a" then Just ((show k) ++ ":new a") else Nothing
    updateLookupWithKey f 5 (fromList [(5,"a"), (3,"b")]) == (Just "a", fromList [(3, "b"), (5, "5:new a")])
    updateLookupWithKey f 7 (fromList [(5,"a"), (3,"b")]) == (Nothing,  fromList [(3, "b"), (5, "a")])
    updateLookupWithKey f 3 (fromList [(5,"a"), (3,"b")]) == (Just "b", singleton 5 "a")
    

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