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1. mapped :: Functor f => ASetter (f a) (f b) a b

   microlens	Lens.Micro

   mapped is a setter for everything contained in a functor. You can use it to map over lists, Maybe, or even IO (which is something you can't do with traversed or each). Here mapped is used to turn a value to all non-Nothing values in a list:

   >>> [Just 3,Nothing,Just 5] & mapped.mapped .~ 0
   [Just 0,Nothing,Just 0]
   

   Keep in mind that while mapped is a more powerful setter than each, it can't be used as a getter! This won't work (and will fail with a type error):

   [(1,2),(3,4),(5,6)] ^.. mapped . both
   

2. mapAsWord128 :: ByteArray bs => (Word128 -> Word128) -> bs -> bs

   memory	Data.ByteArray.Mapping

   map blocks of 128 bits of a bytearray, creating a new bytestring of equivalent size where each blocks has been mapped through f no length checking is done. unsafe

3. mapAsWord64 :: ByteArray bs => (Word64 -> Word64) -> bs -> bs

   memory	Data.ByteArray.Mapping

   map blocks of 64 bits of a bytearray, creating a new bytestring of equivalent size where each blocks has been mapped through f no length checking is done. unsafe

4. mapParseError :: Ord e' => (e -> e') -> ParseError s e -> ParseError s e'

   megaparsec	Text.Megaparsec.Error

   Modify the custom data component in a parse error. This could be done via fmap if not for the Ord constraint.

5. mappend :: Monoid a => a -> a -> a

   validity	Data.Validity

   An associative operation NOTE: This method is redundant and has the default implementation mappend = (<>) since base-4.11.0.0. Should it be implemented manually, since mappend is a synonym for (<>), it is expected that the two functions are defined the same way. In a future GHC release mappend will be removed from Monoid.

6. mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b]

   extra	Control.Monad.Extra

   A version of mapMaybe that works with a monadic predicate.

7. mapLeft :: (a -> c) -> Either a b -> Either c b

   extra	Data.Either.Extra

   The mapLeft function takes a function and applies it to an Either value iff the value takes the form Left _.

   mapLeft show (Left 1) == Left "1"
   mapLeft show (Right True) == Right True
   

8. mapRight :: (b -> c) -> Either a b -> Either a c

   extra	Data.Either.Extra

   The mapRight function takes a function and applies it to an Either value iff the value takes the form Right _.

   mapRight show (Left 1) == Left 1
   mapRight show (Right True) == Right "True"
   

9. mapLeft :: (a -> c) -> Either a b -> Either c b

   extra	Extra

   The mapLeft function takes a function and applies it to an Either value iff the value takes the form Left _.

   mapLeft show (Left 1) == Left "1"
   mapLeft show (Right True) == Right True
   

10. mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b]

    extra	Extra

    A version of mapMaybe that works with a monadic predicate.

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