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Within LTS Haskell 24.62 (ghc-9.10.3)

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Exact lookup

1. insertLookupWithKey :: Ord k => (k -> a -> a -> a) -> k -> a -> Map k a -> (Maybe a, Map k a)

   rio	RIO.Map

   Combines insert operation with old value retrieval. 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.

2. splitLookup :: Ord k => k -> Map k a -> (Map k a, Maybe a, Map k a)

   rio	RIO.Map

   The expression (splitLookup k map) splits a map just like split but also returns lookup k 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)
   

3. updateLookupWithKey :: Ord k => (k -> a -> Maybe a) -> k -> Map k a -> (Maybe a, Map k a)

   rio	RIO.Map

   Lookup and update. See also updateWithKey. The function returns changed value, if it is updated. 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 "5:new 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")
   

4. defaultMimeLookup :: FileName -> MimeType

   mime-types	Network.Mime

   mimeByExt applied to defaultMimeType and defaultMimeMap.

5. deleteLookup :: IsNode a => Key a -> Graph a -> (Maybe a, Graph a)

   Cabal-syntax	Distribution.Compat.Graph

   O(log V). Lookup and delete. This function returns the deleted value if it existed.

6. insMapLookupNode :: (Ord a, DynGraph g) => NodeMap a -> a -> g a b -> (Bool, g a b, NodeMap a, LNode a)

   fgl	Data.Graph.Inductive.NodeMap

   Act as insMapNode, but return also a boolean set as True if the node was already in the map.

7. mkLookupNode :: Ord a => NodeMap a -> a -> (Bool, LNode a, NodeMap a)

   fgl	Data.Graph.Inductive.NodeMap

   Act as mkNode, but return also a boolean set as True if the node was already in the map.

8. type C_VfsFileLookupFunc = Ptr Vfs -> CString -> Ptr () -> IO Ptr File

   gi-gio	GI.Gio.Callbacks

   Type for the callback on the (unwrapped) C side.

9. type VfsFileLookupFunc = Vfs -> Text -> IO Maybe File

   gi-gio	GI.Gio.Callbacks

   This function type is used by vfsRegisterUriScheme to make it possible for a client to associate an URI scheme to a different File implementation. The client should return a reference to the new file that has been created for uri, or Nothing to continue with the default implementation. Since: 2.50

10. type VfsFileLookupFunc_WithClosures = Vfs -> Text -> Ptr () -> IO Maybe File

    gi-gio	GI.Gio.Callbacks

    This function type is used by vfsRegisterUriScheme to make it possible for a client to associate an URI scheme to a different File implementation. The client should return a reference to the new file that has been created for uri, or Nothing to continue with the default implementation. Since: 2.50

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