Safe Haskell	Safe
Language	Haskell2010

Data.Tuple.Only

Synopsis

newtype Only a = Only {
- fromOnly :: a
}

Documentation

newtype Only a Source #

The 1-tuple type or single-value "collection".

This type is structurally equivalent to the Identity type, but its intent is more about serving as the anonymous 1-tuple type missing from Haskell for attaching typeclass instances.

Parameter usage example:

encodeSomething (Only (42::Int))

Result usage example:

xs <- decodeSomething
forM_ xs $ \(Only id) -> {- ... -}

Constructors

Only
Fields fromOnly :: a

Instances

Instances details

Functor Only Source #
Instance details Defined in Data.Tuple.Only Methods fmap :: (a -> b) -> Only a -> Only b Source # (<$) :: a -> Only b -> Only a Source #
Eq a => Eq ( Only a) Source #
Instance details Defined in Data.Tuple.Only Methods (==) :: Only a -> Only a -> Bool Source # (/=) :: Only a -> Only a -> Bool Source #
Data a => Data ( Only a) Source #
Instance details Defined in Data.Tuple.Only Methods gfoldl :: ( forall d b. Data d => c (d -> b) -> d -> c b) -> ( forall g. g -> c g) -> Only a -> c ( Only a) Source # gunfold :: ( forall b r. Data b => c (b -> r) -> c r) -> ( forall r. r -> c r) -> Constr -> c ( Only a) Source # toConstr :: Only a -> Constr Source # dataTypeOf :: Only a -> DataType Source # dataCast1 :: Typeable t => ( forall d. Data d => c (t d)) -> Maybe (c ( Only a)) Source # dataCast2 :: Typeable t => ( forall d e. ( Data d, Data e) => c (t d e)) -> Maybe (c ( Only a)) Source # gmapT :: ( forall b. Data b => b -> b) -> Only a -> Only a Source # gmapQl :: (r -> r' -> r) -> r -> ( forall d. Data d => d -> r') -> Only a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> ( forall d. Data d => d -> r') -> Only a -> r Source # gmapQ :: ( forall d. Data d => d -> u) -> Only a -> [u] Source # gmapQi :: Int -> ( forall d. Data d => d -> u) -> Only a -> u Source # gmapM :: Monad m => ( forall d. Data d => d -> m d) -> Only a -> m ( Only a) Source # gmapMp :: MonadPlus m => ( forall d. Data d => d -> m d) -> Only a -> m ( Only a) Source # gmapMo :: MonadPlus m => ( forall d. Data d => d -> m d) -> Only a -> m ( Only a) Source #
Ord a => Ord ( Only a) Source #
Instance details Defined in Data.Tuple.Only Methods compare :: Only a -> Only a -> Ordering Source # (<) :: Only a -> Only a -> Bool Source # (<=) :: Only a -> Only a -> Bool Source # (>) :: Only a -> Only a -> Bool Source # (>=) :: Only a -> Only a -> Bool Source # max :: Only a -> Only a -> Only a Source # min :: Only a -> Only a -> Only a Source #
Read a => Read ( Only a) Source #
Instance details Defined in Data.Tuple.Only Methods readsPrec :: Int -> ReadS ( Only a) Source # readList :: ReadS [ Only a] Source # readPrec :: ReadPrec ( Only a) Source # readListPrec :: ReadPrec [ Only a] Source #
Show a => Show ( Only a) Source #
Instance details Defined in Data.Tuple.Only Methods showsPrec :: Int -> Only a -> ShowS Source # show :: Only a -> String Source # showList :: [ Only a] -> ShowS Source #
Generic ( Only a) Source #
Instance details Defined in Data.Tuple.Only Associated Types type Rep ( Only a) :: Type -> Type Source # Methods from :: Only a -> Rep ( Only a) x Source # to :: Rep ( Only a) x -> Only a Source #
NFData a => NFData ( Only a) Source #
Instance details Defined in Data.Tuple.Only Methods rnf :: Only a -> () Source #
type Rep ( Only a) Source #
Instance details Defined in Data.Tuple.Only type Rep ( Only a) = D1 (' MetaData "Only" "Data.Tuple.Only" "Only-0.1-5HMnGEdyovGeWGWSTFEMo" ' True ) ( C1 (' MetaCons "Only" ' PrefixI ' True ) ( S1 (' MetaSel (' Just "fromOnly") ' NoSourceUnpackedness ' NoSourceStrictness ' DecidedLazy ) ( Rec0 a)))