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  1. mapMaybe :: (a -> Maybe b) -> Infinite a -> Infinite b

    infinite-list Data.List.Infinite

    Apply a function to every element of an infinite list and collect Just results. This function isn't productive (e. g., head . mapMaybe f won't terminate), if no elements of the input list result in Just.

  2. mapMonotonic :: (a -> c) -> Bimap a b -> Bimap c b

    bimap Data.Bimap

    O(n). Map a strictly increasing function over all left keys in the map. The precondition is not checked. Version 0.3

  3. mapMonotonicR :: (b -> c) -> Bimap a b -> Bimap a c

    bimap Data.Bimap

    O(n). Map a strictly increasing function over all right keys in the map. The precondition is not checked. Version 0.3

  4. mapMaybe :: (a -> Maybe b) -> EnumMap k a -> EnumMap k b

    enummapset Data.EnumMap.Lazy

    No documentation available.

  5. mapMaybeWithKey :: Enum k => (k -> a -> Maybe b) -> EnumMap k a -> EnumMap k b

    enummapset Data.EnumMap.Lazy

    No documentation available.

  6. mapMaybe :: (a -> Maybe b) -> EnumMap k a -> EnumMap k b

    enummapset Data.EnumMap.Strict

    No documentation available.

  7. mapMaybeWithKey :: Enum k => (k -> a -> Maybe b) -> EnumMap k a -> EnumMap k b

    enummapset Data.EnumMap.Strict

    No documentation available.

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

    ghc-internal GHC.Internal.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 ()

    ghc-internal GHC.Internal.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) -> [a] -> [b]

    ghc-internal GHC.Internal.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]

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