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1. mapM :: (Traversable t, Monad m) => (a -> m b) -> t a -> m (t b)

   classy-prelude	ClassyPrelude

   Map each element of a structure to a monadic action, evaluate these actions from left to right, and collect the results. For a version that ignores the results see mapM_.

   Examples

   mapM is literally a traverse with a type signature restricted to Monad. Its implementation may be more efficient due to additional power of Monad.

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

   classy-prelude	ClassyPrelude

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

   classy-prelude	ClassyPrelude

   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.

4. mapAssocs :: Map key value -> Unfoldl (key, value)

   deferred-folds	DeferredFolds.Unfoldl

   Associations of a map

5. mapFoldInput :: (forall x . () => Fold b x -> Fold a x) -> Unfoldl a -> Unfoldl b

   deferred-folds	DeferredFolds.Unfoldl

   Lift a fold input mapping function into a mapping of unfolds

6. mapFoldMInput :: forall (m :: Type -> Type) b a . Monad m => (forall x . () => FoldM m b x -> FoldM m a x) -> UnfoldlM m a -> UnfoldlM m b

   deferred-folds	DeferredFolds.UnfoldlM

   Lift a fold input mapping function into a mapping of unfolds

7. mapM_ :: Monad m => (input -> m ()) -> UnfoldlM m input -> m ()

   deferred-folds	DeferredFolds.UnfoldlM

   A more efficient implementation of mapM_

8. mapAssocs :: Map key value -> Unfoldr (key, value)

   deferred-folds	DeferredFolds.Unfoldr

   Associations of a map

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

   essence-of-live-coding	LiveCoding

   Laws:

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

10. mapExceptionT :: (m (Either SomeException a) -> n (Either SomeException b)) -> ExceptionT m a -> ExceptionT n b

    exception-transformers	Control.Monad.Exception

    No documentation available.

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