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

   ghc-lib	GHC.HsToCore.Monad

   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. mapM :: forall m (u :: Type -> Type) a (v :: Type -> Type) b c d . (Monad m, Vector u a, Vector v b, Vector u c, Vector v d) => ((a, b) -> m (c, d)) -> Vector u v (a, b) -> m (Vector u v (c, d))

   hybrid-vectors	Data.Vector.Hybrid

   O(n) Apply the monadic action to all elements of the vector, yielding a vector of results

3. mapM :: MonadUnliftIO m => (a -> m b) -> InputStream a -> m (InputStream b)

   unliftio-streams	UnliftIO.Streams.Combinators

   No documentation available.

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

   xmonad-contrib	XMonad.Config.Prime

   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.

5. type family MapM (arg :: a ~> m b) (arg1 :: t a) :: m t b

   singletons-base	Control.Monad.Singletons

   No documentation available.

6. mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m ()

   base	Prelude

   Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM. mapM_ is just like traverse_, but specialised to monadic actions.

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

   base	Data.Maybe

   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]
   

8. mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m ()

   base	Control.Monad

   Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM. mapM_ is just like traverse_, but specialised to monadic actions.

9. mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m ()

   base	Data.Foldable

   Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM. mapM_ is just like traverse_, but specialised to monadic actions.

10. mapMaybe :: (a -> Maybe b) -> IntMap a -> IntMap b

    containers	Data.IntMap.Internal

    Map values and collect the Just results.

    let f x = if x == "a" then Just "new a" else Nothing
    mapMaybe f (fromList [(5,"a"), (3,"b")]) == singleton 5 "new a"
    

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