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  1. formParamMaybe :: forall (m :: Type -> Type) a . (MonadUnliftIO m, Parsable a) => Text -> ActionT m (Maybe a)

    scotty Web.Scotty.Trans.Strict

    Look up a form parameter. Returns Nothing if the parameter is not found or cannot be parsed at the right type. NB : Doesn't throw exceptions, so developers must raiseStatus or throw to signal something went wrong. Since: 0.21

  2. queryParamMaybe :: forall a (m :: Type -> Type) . (Parsable a, Monad m) => Text -> ActionT m (Maybe a)

    scotty Web.Scotty.Trans.Strict

    Look up a query parameter. Returns Nothing if the parameter is not found or cannot be parsed at the right type. NB : Doesn't throw exceptions, so developers must raiseStatus or throw to signal something went wrong. Since: 0.21

  3. mapMaybe :: (a -> Maybe b) -> EnumMap k a -> EnumMap k b

    enummapset Data.EnumMap.Lazy

    No documentation available.

  4. mapMaybeWithKey :: Enum k => (k -> a -> Maybe b) -> EnumMap k a -> EnumMap k b

    enummapset Data.EnumMap.Lazy

    No documentation available.

  5. mapMaybe :: (a -> Maybe b) -> EnumMap k a -> EnumMap k b

    enummapset Data.EnumMap.Strict

    No documentation available.

  6. mapMaybeWithKey :: Enum k => (k -> a -> Maybe b) -> EnumMap k a -> EnumMap k b

    enummapset Data.EnumMap.Strict

    No documentation available.

  7. bitSizeMaybe :: Bits a => a -> Maybe Int

    ghc-internal GHC.Internal.Bits

    Return the number of bits in the type of the argument. The actual value of the argument is ignored. Returns Nothing for types that do not have a fixed bitsize, like Integer.

  8. bitSizeMaybe :: Bits a => a -> Maybe Int

    ghc-internal GHC.Internal.Data.Bits

    Return the number of bits in the type of the argument. The actual value of the argument is ignored. Returns Nothing for types that do not have a fixed bitsize, like Integer.

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

    ghc-internal GHC.Internal.Data.Maybe

    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]

  10. fromMaybe :: a -> Maybe a -> a

    ghc-internal GHC.Internal.Data.Maybe

    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

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