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1. bindFromMaybeCharToLifted :: Parser s e (# (# #) | Char# #) -> ((# (# #) | Char# #) -> Parser s e a) -> Parser s e a

   bytesmith	Data.Bytes.Parser

   No documentation available.

2. parseBytesMaybe :: (forall s . () => Parser e s a) -> Bytes -> Maybe a

   bytesmith	Data.Bytes.Parser

   Variant of parseBytesEither that discards the error message on failure. Just like parseBytesEither, this does not impose any checks on the length of the remaining input.

3. type SourceRepoMaybe = SourceRepositoryPackage Maybe

   cabal-install-parsers	Cabal.SourceRepo

   Distilled from SourceRepo

4. catMaybes :: (Contiguous arr, Element arr a, Element arr (Maybe a)) => arr (Maybe a) -> arr a

   contiguous	Data.Primitive.Contiguous

   The catMaybes function takes a list of Maybes and returns a list of all the Just values.

5. mapMaybe :: forall arr1 arr2 a b . (Contiguous arr1, Element arr1 a, Contiguous arr2, Element arr2 b) => (a -> Maybe b) -> arr1 a -> arr2 b

   contiguous	Data.Primitive.Contiguous

   The mapMaybe function is a version of map which can throw out elements. In particular, the functional arguments returns something of type Maybe b. If this is Nothing, no element is added on to the result array. If it is Just b, then b is included in the result array.

6. mapMaybe :: Ord k => (a -> Maybe b) -> Map k a -> Map k b

   dhall	Dhall.Map

   Transform all values in a Map using the supplied function, deleting the key if the function returns Nothing

   >>> mapMaybe Data.Maybe.listToMaybe (fromList [("C",[1]),("B",[]),("A",[3])])
   fromList [("C",1),("A",3)]
   

7. catMaybes :: [Maybe a] -> [a]

   foundation	Foundation

   The catMaybes function takes a list of Maybes and returns a list of all the Just values.

   Examples

   Basic usage:

   >>> catMaybes [Just 1, Nothing, Just 3]
   [1,3]
   

   When constructing a list of Maybe values, catMaybes can be used to return all of the "success" results (if the list is the result of a map, then mapMaybe would be more appropriate):

   >>> import GHC.Internal.Text.Read ( readMaybe )
   
   >>> [readMaybe x :: Maybe Int | x <- ["1", "Foo", "3"] ]
   [Just 1,Nothing,Just 3]
   
   >>> catMaybes $ [readMaybe x :: Maybe Int | x <- ["1", "Foo", "3"] ]
   [1,3]
   

8. fromMaybe :: a -> Maybe a -> a

   foundation	Foundation

   The fromMaybe function takes a default value and a Maybe value. If the Maybe is Nothing, it returns the default value; otherwise, it returns the value contained in the Maybe.

   Examples

   Basic usage:

   >>> fromMaybe "" (Just "Hello, World!")
   "Hello, World!"
   

   >>> fromMaybe "" Nothing
   ""
   

   Read an integer from a string using readMaybe. If we fail to parse an integer, we want to return 0 by default:

   >>> import GHC.Internal.Text.Read ( readMaybe )
   
   >>> fromMaybe 0 (readMaybe "5")
   5
   
   >>> fromMaybe 0 (readMaybe "")
   0
   

9. listToMaybe :: [a] -> Maybe a

   foundation	Foundation

   The listToMaybe function returns Nothing on an empty list or Just a where a is the first element of the list.

   Examples

   Basic usage:

   >>> listToMaybe []
   Nothing
   

   >>> listToMaybe [9]
   Just 9
   

   >>> listToMaybe [1,2,3]
   Just 1
   

   Composing maybeToList with listToMaybe should be the identity on singleton/empty lists:

   >>> maybeToList $ listToMaybe [5]
   [5]
   
   >>> maybeToList $ listToMaybe []
   []
   

   But not on lists with more than one element:

   >>> maybeToList $ listToMaybe [1,2,3]
   [1]
   

10. mapMaybe :: (a -> Maybe b) -> [a] -> [b]

    foundation	Foundation

    The mapMaybe function is a version of map which can throw out elements. In particular, the functional argument returns something of type Maybe b. If this is Nothing, no element is added on to the result list. If it is Just b, then b is included in the result list.

    Examples

    Using mapMaybe f x is a shortcut for catMaybes $ map f x in most cases:

    >>> import GHC.Internal.Text.Read ( readMaybe )
    
    >>> let readMaybeInt = readMaybe :: String -> Maybe Int
    
    >>> mapMaybe readMaybeInt ["1", "Foo", "3"]
    [1,3]
    
    >>> catMaybes $ map readMaybeInt ["1", "Foo", "3"]
    [1,3]
    

    If we map the Just constructor, the entire list should be returned:

    >>> mapMaybe Just [1,2,3]
    [1,2,3]
    

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