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mapMaybe :: forall (m :: Type -> Type) a b r . Functor m => (a -> Maybe b) -> Pipe a b m rpipes Pipes.Prelude (mapMaybe f) yields Just results of f. Basic laws:
mapMaybe (f >=> g) = mapMaybe f >-> mapMaybe g mapMaybe (pure @Maybe . f) = mapMaybe (Just . f) = map f mapMaybe (const Nothing) = drain
As a result of the second law,mapMaybe return = mapMaybe Just = cat
mapCArrayWithLength :: (Storable a, Integral b) => b -> (a -> IO c) -> Ptr a -> IO ()haskell-gi-base Data.GI.Base.BasicConversions No documentation available.
mapGArray :: Storable a => (a -> IO b) -> Ptr (GArray a) -> IO ()haskell-gi-base Data.GI.Base.BasicConversions No documentation available.
mapGList :: (Ptr a -> IO b) -> Ptr (GList (Ptr a)) -> IO ()haskell-gi-base Data.GI.Base.BasicConversions No documentation available.
mapGSList :: (Ptr a -> IO b) -> Ptr (GSList (Ptr a)) -> IO ()haskell-gi-base Data.GI.Base.BasicConversions No documentation available.
mapPtrArray :: (Ptr a -> IO b) -> Ptr (GPtrArray (Ptr a)) -> IO ()haskell-gi-base Data.GI.Base.BasicConversions No documentation available.
mapZeroTerminatedCArray :: (Ptr a -> IO b) -> Ptr (Ptr a) -> IO ()haskell-gi-base Data.GI.Base.BasicConversions No documentation available.
mapGValueArrayWithLength :: Integral a => a -> (Ptr GValue -> IO c) -> Ptr GValue -> IO ()haskell-gi-base Data.GI.Base.GValue Map over the GValues inside a C array.
mapM :: (Traversable t, Monad m) => (a -> m b) -> t a -> m (t b)haskell-gi-base Data.GI.Base.ShortPrelude 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.mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m ()haskell-gi-base Data.GI.Base.ShortPrelude 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.