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  1. class ReifyMaybeSymbol (mstr :: Maybe Symbol)

    bytezap Bytezap.Parser.Struct.Generic

    No documentation available.

  2. reifyMaybeSymbol :: ReifyMaybeSymbol mstr => Maybe String

    bytezap Bytezap.Parser.Struct.Generic

    No documentation available.

  3. ByMaybeAttr :: WhyNullable

    classy-prelude-yesod ClassyPrelude.Yesod

    No documentation available.

  4. FieldAttrMaybe :: FieldAttr

    classy-prelude-yesod ClassyPrelude.Yesod

    The Maybe keyword goes after the type. This indicates that the column is nullable, and the generated Haskell code will have a Maybe type for it. Example: 

    User
name Text Maybe

  5. asMaybe :: Maybe a -> Maybe a

    classy-prelude-yesod ClassyPrelude.Yesod

    No documentation available.

  6. 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

  7. 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

  8. 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

  9. isFieldMaybe :: FieldDef -> Bool

    classy-prelude-yesod ClassyPrelude.Yesod

    Check if the field is `Maybe a`

  10. 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]

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