Hoogle Search

Within LTS Haskell 24.6 (ghc-9.10.2)

Note that Stackage only displays results for the latest LTS and Nightly snapshot. Learn more.

Exact lookup

1. mapMaybe :: (v1 -> Maybe v2) -> HashMap k v1 -> HashMap k v2

   unordered-containers	Data.HashMap.Internal

   Transform this map by applying a function to every value and retaining only some of them.

2. mapMaybe :: (v1 -> Maybe v2) -> HashMap k v1 -> HashMap k v2

   unordered-containers	Data.HashMap.Internal.Strict

   Transform this map by applying a function to every value and retaining only some of them.

3. mapMaybe :: (v1 -> Maybe v2) -> HashMap k v1 -> HashMap k v2

   unordered-containers	Data.HashMap.Lazy

   Transform this map by applying a function to every value and retaining only some of them.

4. mapMaybe :: (v1 -> Maybe v2) -> HashMap k v1 -> HashMap k v2

   unordered-containers	Data.HashMap.Strict

   Transform this map by applying a function to every value and retaining only some of them.

5. mapMaybe :: forall (m :: Type -> Type) a b . Monad m => (a -> Maybe b) -> ConduitT a b m ()

   conduit	Data.Conduit.List

   Apply a transformation that may fail to all values in a stream, discarding the failures. Subject to fusion Since 0.5.1

6. mapMaybe :: (MonadGen m, GenBase m ~ Identity) => (a -> Maybe b) -> m a -> m b

   hedgehog	Hedgehog.Gen

   Generates a value which is the result of the given function returning a Just. The original generator's shrink tree will be retained, with values returning Nothing removed. Subsequent shrinks of those values will be retained. Compared to mapMaybeT, shrinking may be slower but will be optimal. It's possible that the function will never return Just, or will only do so a larger size than we're currently running at. To avoid looping forever, we limit the number of retries, and grow the size with each retry. If we retry too many times then the whole generator is discarded.

7. mapMaybe :: (MonadGen m, GenBase m ~ Identity) => (a -> Maybe b) -> m a -> m b

   hedgehog	Hedgehog.Internal.Gen

   Generates a value which is the result of the given function returning a Just. The original generator's shrink tree will be retained, with values returning Nothing removed. Subsequent shrinks of those values will be retained. Compared to mapMaybeT, shrinking may be slower but will be optimal. It's possible that the function will never return Just, or will only do so a larger size than we're currently running at. To avoid looping forever, we limit the number of retries, and grow the size with each retry. If we retry too many times then the whole generator is discarded.

8. mapMaybe :: (a -> Maybe b) -> Tree a -> Maybe (Tree b)

   hedgehog	Hedgehog.Internal.Tree

   No documentation available.

9. mapMaybe :: forall (m :: Type -> Type) a b . Functor m => (a -> Maybe b) -> SourceT m a -> SourceT m b

   servant	Servant.Types.SourceT

   Filter values.

   >>> toList $ mapMaybe (\x -> if odd x then Just x else Nothing) (source [0..10]) :: [Int]
   [1,3,5,7,9]
   

   >>> mapMaybe (\x -> if odd x then Just x else Nothing) (source [0..2]) :: SourceT Identity Int
   fromStepT (Effect (Identity (Skip (Yield 1 (Skip Stop)))))
   

   Illustrates why we need Skip.

10. mapMaybe :: (a -> Maybe b) -> Word64Map a -> Word64Map b

    ghc	GHC.Data.Word64Map.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"
    

Page 2 of many | Previous | Next