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1. minusMaybe :: (Ord k, MonoidNull v, Reductive v) => MonoidMap k v -> MonoidMap k v -> Maybe (MonoidMap k v)

   monoidmap-internal	Data.MonoidMap.Internal

   Performs reductive subtraction of the second map from the first. Uses the Reductive subtraction operator (</>) to subtract each value in the second map from its matching value in the first map. This function produces a result if (and only if) for all possible keys k, it is possible to subtract the value for k in the second map from the value for k in the first map:

   isJust (m1 `minusMaybe` m2)
   == (∀ k. isJust (get k m1 </> get k m2))
   

   Otherwise, this function returns Nothing. This function satisfies the following property:

   all
   (\r -> Just (get k r) == get k m1 </> get k m2)
   (m1 `minusMaybe` m2)
   

   This function provides the definition of (</>) for the MonoidMap instance of Reductive.

   Examples

   With Set Natural values, this function performs set subtraction of matching values, succeeding if (and only if) each value from the second map is a subset of its matching value from the first map:

   f xs = fromList (fromList <$> xs)
   

   >>> m1 = f [("a", [0,1,2]), ("b", [0,1,2])]
   >>> m2 = f [("a", [     ]), ("b", [0,1,2])]
   >>> m3 = f [("a", [0,1,2]), ("b", [     ])]
   

   >>> m1 `minusMaybe` m2 == Just m3
   True
   

   >>> m1 = f [("a", [0,1,2]), ("b", [0,1,2]), ("c", [0,1,2])]
   >>> m2 = f [("a", [0    ]), ("b", [  1  ]), ("c", [    2])]
   >>> m3 = f [("a", [  1,2]), ("b", [0,  2]), ("c", [0,1  ])]
   

   >>> m1 `minusMaybe` m2 == Just m3
   True
   

   >>> m1 = f [("a", [0,1,2    ]), ("b", [0,1,2    ]), ("c", [0,1,2    ])]
   >>> m2 = f [("a", [    2,3,4]), ("b", [  1,2,3,4]), ("c", [0,1,2,3,4])]
   

   >>> m1 `minusMaybe` m2 == Nothing
   True
   

   With Sum Natural values, this function performs ordinary subtraction of matching values, succeeding if (and only if) each value from the second map is less than or equal to its matching value from the first map:

   >>> m1 = fromList [("a", 2), ("b", 3), ("c", 5), ("d", 8)]
   >>> m2 = fromList [("a", 0), ("b", 0), ("c", 0), ("d", 0)]
   >>> m3 = fromList [("a", 2), ("b", 3), ("c", 5), ("d", 8)]
   

   >>> m1 `minusMaybe` m2 == Just m3
   True
   

   >>> m1 = fromList [("a", 2), ("b", 3), ("c", 5), ("d", 8)]
   >>> m2 = fromList [("a", 1), ("b", 2), ("c", 3), ("d", 5)]
   >>> m3 = fromList [("a", 1), ("b", 1), ("c", 2), ("d", 3)]
   

   >>> m1 `minusMaybe` m2 == Just m3
   True
   

   >>> m1 = fromList [("a", 2), ("b", 3), ("c", 5), ("d", 8)]
   >>> m2 = fromList [("a", 2), ("b", 3), ("c", 5), ("d", 8)]
   >>> m3 = fromList [("a", 0), ("b", 0), ("c", 0), ("d", 0)]
   

   >>> m1 `minusMaybe` m2 == Just m3
   True
   

   >>> m1 = fromList [("a", 2), ("b", 3), ("c", 5), ("d", 8)]
   >>> m2 = fromList [("a", 3), ("b", 3), ("c", 5), ("d", 8)]
   

   >>> m1 `minusMaybe` m2 == Nothing
   True
   

2. mapMaybe :: (Key -> Maybe Key) -> IntMultiSet -> IntMultiSet

   multiset	Data.IntMultiSet

   O(n). Map and collect the Just results.

3. mapMaybe :: Ord b => (a -> Maybe b) -> MultiSet a -> MultiSet b

   multiset	Data.MultiSet

   O(n). Map and collect the Just results.

4. optionMaybe :: forall s (m :: Type -> Type) t u a . Stream s m t => ParsecT s u m a -> ParsecT s u m (Maybe a)

   parsec-class	Text.Parsec.Class

   optionMaybe p tries to apply parser p. If p fails without consuming input, it return Nothing, otherwise it returns Just the value returned by p.

5. fromMaybeOrd :: Maybe Ordering -> PartialOrdering

   partialord	Data.PartialOrd

   Convert an ordering into a partial ordering

6. toMaybeOrd :: PartialOrdering -> Maybe Ordering

   partialord	Data.PartialOrd

   Convert a partial ordering to an ordering

7. readMaybe_ :: Read a => String -> Maybe a

   pontarius-xmpp	Network.Xmpp.Internal

   No documentation available.

8. prefixMaybe :: (a -> TextBuilder) -> Maybe a -> TextBuilder

   postgresql-syntax	PostgresqlSyntax.Rendering

   No documentation available.

9. suffixMaybe :: (a -> TextBuilder) -> Maybe a -> TextBuilder

   postgresql-syntax	PostgresqlSyntax.Rendering

   No documentation available.

10. toMaybeList :: By6Bits e -> [Maybe e]

    primitive-extras	PrimitiveExtras.By6Bits

    Convert into a list representation.

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