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Within LTS Haskell 24.3 (ghc-9.10.2)

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  1. data MaybeKT (m :: Type -> Type) a

    unification-fd Control.Monad.MaybeK

    A monad transformer version of MaybeK.

  2. type MaybeMaybeManageHook = Query Maybe Maybe Endo WindowSet

    xmonad-contrib XMonad.Hooks.FloatConfigureReq

    A variant of MaybeManageHook that additionally may or may not make changes to the WindowSet.

  3. type MaybeManageHook = Query Maybe Endo WindowSet

    xmonad-contrib XMonad.Hooks.ManageHelpers

    A ManageHook that may or may not have been executed; the outcome is embedded in the Maybe

  4. maybeToList :: Maybe a -> [a]

    base Data.Maybe

    The maybeToList function returns an empty list when given Nothing or a singleton list when given Just.

    Examples

    Basic usage: 
    >>> maybeToList (Just 7)
[7]

    >>> maybeToList Nothing
[]
    One can use maybeToList to avoid pattern matching when combined with a function that (safely) works on lists: 
    >>> import GHC.Internal.Text.Read ( readMaybe )

>>> sum $ maybeToList (readMaybe "3")
3

>>> sum $ maybeToList (readMaybe "")
0

  5. maybeNew :: (a -> IO (Ptr b)) -> Maybe a -> IO (Ptr b)

    base Foreign.Marshal.Utils

    Allocate storage and marshal a storable value wrapped into a Maybe

  6. maybePeek :: (Ptr a -> IO b) -> Ptr a -> IO (Maybe b)

    base Foreign.Marshal.Utils

    Convert a peek combinator into a one returning Nothing if applied to a nullPtr

  7. maybeWith :: (a -> (Ptr b -> IO c) -> IO c) -> Maybe a -> (Ptr b -> IO c) -> IO c

    base Foreign.Marshal.Utils

    Converts a withXXX combinator into one marshalling a value wrapped into a Maybe, using nullPtr to represent Nothing.

  8. maybeToExceptT :: forall (m :: Type -> Type) e a . Functor m => e -> MaybeT m a -> ExceptT e m a

    transformers Control.Monad.Trans.Maybe

    Convert a MaybeT computation to ExceptT, with a default exception value.

  9. maybeToListT :: Applicative m => m (Maybe a) -> ListT m a

    directory System.Directory.Internal

    No documentation available.

  10. maybeResult :: Result r -> Maybe r

    attoparsec Data.Attoparsec.ByteString

    Convert a Result value to a Maybe value. A Partial result is treated as failure.

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