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1. mapMOf :: LensLike (WrappedMonad m) s t a b -> (a -> m b) -> s -> m t

   microlens	Lens.Micro

   Map each element of a structure targeted by a Lens to a monadic action, evaluate these actions from left to right, and collect the results.

   >>> mapMOf both (\x -> [x, x + 1]) (1,3)
   [(1,3),(1,4),(2,3),(2,4)]
   

2. 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
   

3. 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

4. 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

5. mapLeafBenchmarks :: ([String] -> Benchmark -> Benchmark) -> Benchmark -> Benchmark

   tasty-bench	Test.Tasty.Bench

   Map leaf benchmarks (bench, not bgroup) with a provided function, which has an access to leaf's reversed path. This helper is useful for bulk application of bcompare. See also locateBenchmark. Real world examples:

   • https://hackage.haskell.org/package/chimera-0.3.3.0/src/bench/Bench.hs
   • https://hackage.haskell.org/package/text-builder-linear-0.1.1/src/bench/Main.hs

6. 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
   

7. 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
   

8. 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.

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

   extra	Control.Monad.Extra

   A version of mapMaybe that works with a monadic predicate.

10. 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
    

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