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

   relude	Relude.Monad.Reexport

   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]
   

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

   relude	Relude.Monad.Reexport

   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]
   

3. runMaybeT :: MaybeT (m :: Type -> Type) a -> m (Maybe a)

   relude	Relude.Monad.Reexport

   No documentation available.

4. hoistMaybe :: forall (m :: Type -> Type) a . Applicative m => Maybe a -> MaybeT m a

   relude	Relude.Monad.Trans

   Lift a Maybe to the MaybeT monad

5. readMaybe :: Read a => String -> Maybe a

   relude	Relude.String.Reexport

   Parse a string using the Read instance. Succeeds if there is exactly one valid result.

   >>> readMaybe "123" :: Maybe Int
   Just 123
   

   >>> readMaybe "hello" :: Maybe Int
   Nothing
   

6. mapMaybe :: Ord key => key -> Accessor (Map key elem) (Maybe elem)

   distributed-process	Control.Distributed.Process.Internal.StrictContainerAccessors

   No documentation available.

7. data FromMaybe (a :: k) (b :: Maybe k) (c :: k)

   first-class-families	Fcf

   No documentation available.

8. data UnMaybe (c :: Exp b) (d :: a -> Exp b) (e :: Maybe a) (f :: b)

   first-class-families	Fcf

   No documentation available.

9. data FromMaybe (a :: k) (b :: Maybe k) (c :: k)

   first-class-families	Fcf.Data.Common

   No documentation available.

10. data UnMaybe (c :: Exp b) (d :: a -> Exp b) (e :: Maybe a) (f :: b)

    first-class-families	Fcf.Data.Common

    No documentation available.

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