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1. asMaybe :: Maybe a -> Maybe a

   classy-prelude-yesod	ClassyPrelude.Yesod

   No documentation available.

2. catMaybes :: (IsSequence (f (Maybe t)), Functor f, Element (f (Maybe t)) ~ Maybe t) => f (Maybe t) -> f t

   classy-prelude-yesod	ClassyPrelude.Yesod

   Takes all of the Just values from a sequence of Maybe ts and concatenates them into an unboxed sequence of ts. Since 0.6.2

3. fromMaybe :: a -> Maybe a -> a

   classy-prelude-yesod	ClassyPrelude.Yesod

   The fromMaybe function takes a default value and a Maybe value. If the Maybe is Nothing, it returns the default value; otherwise, it returns the value contained in the Maybe.

   Examples

   Basic usage:

   >>> fromMaybe "" (Just "Hello, World!")
   "Hello, World!"
   

   >>> fromMaybe "" Nothing
   ""
   

   Read an integer from a string using readMaybe. If we fail to parse an integer, we want to return 0 by default:

   >>> import GHC.Internal.Text.Read ( readMaybe )
   
   >>> fromMaybe 0 (readMaybe "5")
   5
   
   >>> fromMaybe 0 (readMaybe "")
   0
   

4. fuseBothMaybe :: forall (m :: Type -> Type) a b r1 c r2 . Monad m => ConduitT a b m r1 -> ConduitT b c m r2 -> ConduitT a c m (Maybe r1, r2)

   classy-prelude-yesod	ClassyPrelude.Yesod

   Like fuseBoth, but does not force consumption of the Producer. In the case that the Producer terminates, the result value is provided as a Just value. If it does not terminate, then a Nothing value is returned. One thing to note here is that "termination" here only occurs if the Producer actually yields a Nothing value. For example, with the Producer mapM_ yield [1..5], if five values are requested, the Producer has not yet terminated. Termination only occurs when the sixth value is awaited for and the Producer signals termination. Since 1.2.4

5. isFieldMaybe :: FieldDef -> Bool

   classy-prelude-yesod	ClassyPrelude.Yesod

   Check if the field is `Maybe a`

6. listToMaybe :: [a] -> Maybe a

   classy-prelude-yesod	ClassyPrelude.Yesod

   The listToMaybe function returns Nothing on an empty list or Just a where a is the first element of the list.

   Examples

   Basic usage:

   >>> listToMaybe []
   Nothing
   

   >>> listToMaybe [9]
   Just 9
   

   >>> listToMaybe [1,2,3]
   Just 1
   

   Composing maybeToList with listToMaybe should be the identity on singleton/empty lists:

   >>> maybeToList $ listToMaybe [5]
   [5]
   
   >>> maybeToList $ listToMaybe []
   []
   

   But not on lists with more than one element:

   >>> maybeToList $ listToMaybe [1,2,3]
   [1]
   

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

   classy-prelude-yesod	ClassyPrelude.Yesod

   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. mapOutputMaybe :: forall (m :: Type -> Type) o1 o2 i r . Monad m => (o1 -> Maybe o2) -> ConduitT i o1 m r -> ConduitT i o2 m r

   classy-prelude-yesod	ClassyPrelude.Yesod

   Same as mapOutput, but use a function that returns Maybe values. Since 0.5.0

9. runMaybeC :: forall (m :: Type -> Type) i o r . Monad m => ConduitT i o (MaybeT m) r -> ConduitT i o m (Maybe r)

   classy-prelude-yesod	ClassyPrelude.Yesod

   Run MaybeT in the base monad Since 1.0.11

10. queryMaybe :: forall (m :: Type -> Type) world a . Monad m => (world 'FieldOf -> Maybe a) -> QueryT world m (Maybe a)

    ecstasy	Data.Ecstasy

    Attempt to get the value of a component.

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