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1. map' :: (Mapping p, Functor f) => p a b -> p (f a) (f b)

   profunctors	Data.Profunctor

   Laws:

   map' . rmap f ≡ rmap (fmap f) . map'
   map' . map' ≡ dimap Compose getCompose . map'
   dimap Identity runIdentity . map' ≡ id
   

2. map' :: (Mapping p, Functor f) => p a b -> p (f a) (f b)

   profunctors	Data.Profunctor.Mapping

   Laws:

   map' . rmap f ≡ rmap (fmap f) . map'
   map' . map' ≡ dimap Compose getCompose . map'
   dimap Identity runIdentity . map' ≡ id
   

3. 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.

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

   extra	Control.Monad.Extra

   A version of mapMaybe that works with a monadic predicate.

5. 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
   

6. 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"
   

7. 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
   

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

   extra	Extra

   A version of mapMaybe that works with a monadic predicate.

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

   extra	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"
   

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

    base-compat	Data.Monoid.Compat

    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.

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