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  1. tyConDataCons_maybe :: TyCon -> Maybe [DataCon]

    liquidhaskell-boot Liquid.GHC.API

    Determine the DataCons originating from the given TyCon, if the TyCon is the sort that can have any constructors (note: this does not include abstract algebraic types)

  2. tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])

    liquidhaskell-boot Liquid.GHC.API

    If this TyCon is that of a data family instance, return the family in question and the instance types. Otherwise, return Nothing

  3. tyConSingleDataCon_maybe :: TyCon -> Maybe DataCon

    liquidhaskell-boot Liquid.GHC.API

    If the given TyCon has a single data constructor, i.e. it is a data type with one alternative, a tuple type or a newtype then that constructor is returned. If the TyCon has more than one constructor, or represents a primitive or function type constructor then Nothing is returned.

  4. parseMaybe :: (a -> Parser b) -> a -> Maybe b

    microaeson Data.Aeson.Micro

    Run Parser. A common use-case is parseMaybe parseJSON.

  5. 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

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

    multiset Data.IntMultiSet

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

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

    multiset Data.MultiSet

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

  8. 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.

  9. fromMaybeOrd :: Maybe Ordering -> PartialOrdering

    partialord Data.PartialOrd

    Convert an ordering into a partial ordering

  10. toMaybeOrd :: PartialOrdering -> Maybe Ordering

    partialord Data.PartialOrd

    Convert a partial ordering to an ordering

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