| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Codec.GlTF.Prelude
Synopsis
- type Size = Int
- class FromJSON a where
- class ToJSON a where
- toJSON :: a -> Value
- toEncoding :: a -> Encoding
- toJSONList :: [a] -> Value
- toEncodingList :: [a] -> Encoding
- class Generic a
- gParseJSON :: _ => Value -> Parser a
- gToJSON :: _ => a -> Value
- data HashMap k v
- type Object = KeyMap Value
- data Scientific
- data Text
- data Value
- data Vector a
- withText :: String -> (Text -> Parser a) -> Value -> Parser a
- withObject :: String -> (Object -> Parser a) -> Value -> Parser a
- (.:) :: FromJSON a => Object -> Key -> Parser a
- (.:?) :: FromJSON a => Object -> Key -> Parser (Maybe a)
- (.!=) :: Parser (Maybe a) -> a -> Parser a
Documentation
A type that can be converted from JSON, with the possibility of failure.
In many cases, you can get the compiler to generate parsing code for you (see below). To begin, let's cover writing an instance by hand.
There are various reasons a conversion could fail. For example, an
Object could be missing a required key, an Array could be of
the wrong size, or a value could be of an incompatible type.
The basic ways to signal a failed conversion are as follows:
failyields a custom error message: it is the recommended way of reporting a failure;empty(ormzero) is uninformative: use it when the error is meant to be caught by some(;<|>)typeMismatchcan be used to report a failure when the encountered value is not of the expected JSON type;unexpectedis an appropriate alternative when more than one type may be expected, or to keep the expected type implicit.
prependFailure (or modifyFailure) add more information to a parser's
error messages.
An example type and instance using typeMismatch and prependFailure:
-- Allow ourselves to writeTextliterals. {-# LANGUAGE OverloadedStrings #-} data Coord = Coord { x :: Double, y :: Double } instanceFromJSONCoord whereparseJSON(Objectv) = Coord<$>v.:"x"<*>v.:"y" -- We do not expect a non-Objectvalue here. -- We could useemptyto fail, buttypeMismatch-- gives a much more informative error message.parseJSONinvalid =prependFailure"parsing Coord failed, " (typeMismatch"Object" invalid)
For this common case of only being concerned with a single
type of JSON value, the functions withObject, withScientific, etc.
are provided. Their use is to be preferred when possible, since
they are more terse. Using withObject, we can rewrite the above instance
(assuming the same language extension and data type) as:
instanceFromJSONCoord whereparseJSON=withObject"Coord" $ \v -> Coord<$>v.:"x"<*>v.:"y"
Instead of manually writing your FromJSON instance, there are two options
to do it automatically:
- Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
- The compiler can provide a default generic implementation for
parseJSON.
To use the second, simply add a deriving clause to your
datatype and declare a GenericFromJSON instance for your datatype without giving
a definition for parseJSON.
For example, the previous example can be simplified to just:
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics
data Coord = Coord { x :: Double, y :: Double } deriving Generic
instance FromJSON Coord
The default implementation will be equivalent to
parseJSON = ; if you need different
options, you can customize the generic decoding by defining:genericParseJSON defaultOptions
customOptions =defaultOptions{fieldLabelModifier=maptoUpper} instanceFromJSONCoord whereparseJSON=genericParseJSONcustomOptions
Minimal complete definition
Nothing
Instances
A type that can be converted to JSON.
Instances in general must specify toJSON and should (but don't need
to) specify toEncoding.
An example type and instance:
-- Allow ourselves to writeTextliterals. {-# LANGUAGE OverloadedStrings #-} data Coord = Coord { x :: Double, y :: Double } instanceToJSONCoord wheretoJSON(Coord x y) =object["x".=x, "y".=y]toEncoding(Coord x y) =pairs("x".=x<>"y".=y)
Instead of manually writing your ToJSON instance, there are two options
to do it automatically:
- Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
- The compiler can provide a default generic implementation for
toJSON.
To use the second, simply add a deriving clause to your
datatype and declare a GenericToJSON instance. If you require nothing other than
defaultOptions, it is sufficient to write (and this is the only
alternative where the default toJSON implementation is sufficient):
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics
data Coord = Coord { x :: Double, y :: Double } deriving Generic
instance ToJSON Coord where
toEncoding = genericToEncoding defaultOptions
If on the other hand you wish to customize the generic decoding, you have to implement both methods:
customOptions =defaultOptions{fieldLabelModifier=maptoUpper} instanceToJSONCoord wheretoJSON=genericToJSONcustomOptionstoEncoding=genericToEncodingcustomOptions
Previous versions of this library only had the toJSON method. Adding
toEncoding had two reasons:
- toEncoding is more efficient for the common case that the output of
toJSONis directly serialized to aByteString. Further, expressing either method in terms of the other would be non-optimal. - The choice of defaults allows a smooth transition for existing users:
Existing instances that do not define
toEncodingstill compile and have the correct semantics. This is ensured by making the default implementation oftoEncodingusetoJSON. This produces correct results, but since it performs an intermediate conversion to aValue, it will be less efficient than directly emitting anEncoding. (this also means that specifying nothing more thaninstance ToJSON Coordwould be sufficient as a generically decoding instance, but there probably exists no good reason to not specifytoEncodingin new instances.)
Minimal complete definition
Nothing
Methods
Convert a Haskell value to a JSON-friendly intermediate type.
toEncoding :: a -> Encoding #
Encode a Haskell value as JSON.
The default implementation of this method creates an
intermediate Value using toJSON. This provides
source-level compatibility for people upgrading from older
versions of this library, but obviously offers no performance
advantage.
To benefit from direct encoding, you must provide an
implementation for this method. The easiest way to do so is by
having your types implement Generic using the DeriveGeneric
extension, and then have GHC generate a method body as follows.
instanceToJSONCoord wheretoEncoding=genericToEncodingdefaultOptions
toJSONList :: [a] -> Value #
toEncodingList :: [a] -> Encoding #
Instances
Representable types of kind *.
This class is derivable in GHC with the DeriveGeneric flag on.
A Generic instance must satisfy the following laws:
from.to≡idto.from≡id
Instances
gParseJSON :: _ => Value -> Parser a Source #
A map from keys to values. A map cannot contain duplicate keys; each key can map to at most one value.
Instances
| Bifoldable HashMap | Since: unordered-containers-0.2.11 |
| Eq2 HashMap | |
| Ord2 HashMap | |
Defined in Data.HashMap.Internal | |
| Show2 HashMap | |
| NFData2 HashMap | Since: unordered-containers-0.2.14.0 |
Defined in Data.HashMap.Internal | |
| Hashable2 HashMap | |
Defined in Data.HashMap.Internal | |
| (Lift k, Lift v) => Lift (HashMap k v :: Type) | Since: unordered-containers-0.2.17.0 |
| Functor (HashMap k) | |
| Foldable (HashMap k) | |
Defined in Data.HashMap.Internal Methods fold :: Monoid m => HashMap k m -> m # foldMap :: Monoid m => (a -> m) -> HashMap k a -> m # foldMap' :: Monoid m => (a -> m) -> HashMap k a -> m # foldr :: (a -> b -> b) -> b -> HashMap k a -> b # foldr' :: (a -> b -> b) -> b -> HashMap k a -> b # foldl :: (b -> a -> b) -> b -> HashMap k a -> b # foldl' :: (b -> a -> b) -> b -> HashMap k a -> b # foldr1 :: (a -> a -> a) -> HashMap k a -> a # foldl1 :: (a -> a -> a) -> HashMap k a -> a # toList :: HashMap k a -> [a] # length :: HashMap k a -> Int # elem :: Eq a => a -> HashMap k a -> Bool # maximum :: Ord a => HashMap k a -> a # minimum :: Ord a => HashMap k a -> a # | |
| Traversable (HashMap k) | |
Defined in Data.HashMap.Internal | |
| ToJSONKey k => ToJSON1 (HashMap k) | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON :: (a -> Value) -> ([a] -> Value) -> HashMap k a -> Value # liftToJSONList :: (a -> Value) -> ([a] -> Value) -> [HashMap k a] -> Value # liftToEncoding :: (a -> Encoding) -> ([a] -> Encoding) -> HashMap k a -> Encoding # liftToEncodingList :: (a -> Encoding) -> ([a] -> Encoding) -> [HashMap k a] -> Encoding # | |
| (FromJSONKey k, Eq k, Hashable k) => FromJSON1 (HashMap k) | |
| Eq k => Eq1 (HashMap k) | |
| Ord k => Ord1 (HashMap k) | |
Defined in Data.HashMap.Internal | |
| (Eq k, Hashable k, Read k) => Read1 (HashMap k) | |
Defined in Data.HashMap.Internal | |
| Show k => Show1 (HashMap k) | |
| NFData k => NFData1 (HashMap k) | Since: unordered-containers-0.2.14.0 |
Defined in Data.HashMap.Internal | |
| Hashable k => Hashable1 (HashMap k) | |
Defined in Data.HashMap.Internal | |
| (Eq k, Hashable k) => IsList (HashMap k v) | |
| (Eq k, Eq v) => Eq (HashMap k v) | Note that, in the presence of hash collisions, equal
In general, the lack of substitutivity can be observed with any function that depends on the key ordering, such as folds and traversals. |
| (Data k, Data v, Eq k, Hashable k) => Data (HashMap k v) | |
Defined in Data.HashMap.Internal Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> HashMap k v -> c (HashMap k v) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (HashMap k v) # toConstr :: HashMap k v -> Constr # dataTypeOf :: HashMap k v -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (HashMap k v)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (HashMap k v)) # gmapT :: (forall b. Data b => b -> b) -> HashMap k v -> HashMap k v # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> HashMap k v -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> HashMap k v -> r # gmapQ :: (forall d. Data d => d -> u) -> HashMap k v -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> HashMap k v -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> HashMap k v -> m (HashMap k v) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> HashMap k v -> m (HashMap k v) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> HashMap k v -> m (HashMap k v) # | |
| (Ord k, Ord v) => Ord (HashMap k v) | The ordering is total and consistent with the |
Defined in Data.HashMap.Internal | |
| (Eq k, Hashable k, Read k, Read e) => Read (HashMap k e) | |
| (Show k, Show v) => Show (HashMap k v) | |
| (Eq k, Hashable k) => Semigroup (HashMap k v) | If a key occurs in both maps, the mapping from the first will be the mapping in the result. Examples
|
| (Eq k, Hashable k) => Monoid (HashMap k v) | If a key occurs in both maps, the mapping from the first will be the mapping in the result. Examples
|
| (Hashable k, Hashable v) => Hashable (HashMap k v) | |
Defined in Data.HashMap.Internal | |
| (ToJSON v, ToJSONKey k) => ToJSON (HashMap k v) | |
Defined in Data.Aeson.Types.ToJSON | |
| (FromJSON v, FromJSONKey k, Eq k, Hashable k) => FromJSON (HashMap k v) | |
| (NFData k, NFData v) => NFData (HashMap k v) | |
Defined in Data.HashMap.Internal | |
| type Item (HashMap k v) | |
Defined in Data.HashMap.Internal | |
data Scientific #
An arbitrary-precision number represented using scientific notation.
This type describes the set of all Reals
A scientific number with coefficient c and base10Exponent e
corresponds to the Fractional number: fromInteger c * 10 ^^ e
Instances
| Eq Scientific | Scientific numbers can be safely compared for equality. No magnitude |
Defined in Data.Scientific | |
| Fractional Scientific | WARNING: These methods also compute
|
Defined in Data.Scientific Methods (/) :: Scientific -> Scientific -> Scientific # recip :: Scientific -> Scientific # fromRational :: Rational -> Scientific # | |
| Data Scientific | |
Defined in Data.Scientific Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Scientific -> c Scientific # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Scientific # toConstr :: Scientific -> Constr # dataTypeOf :: Scientific -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Scientific) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Scientific) # gmapT :: (forall b. Data b => b -> b) -> Scientific -> Scientific # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Scientific -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Scientific -> r # gmapQ :: (forall d. Data d => d -> u) -> Scientific -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Scientific -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Scientific -> m Scientific # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Scientific -> m Scientific # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Scientific -> m Scientific # | |
| Num Scientific | WARNING: |
Defined in Data.Scientific Methods (+) :: Scientific -> Scientific -> Scientific # (-) :: Scientific -> Scientific -> Scientific # (*) :: Scientific -> Scientific -> Scientific # negate :: Scientific -> Scientific # abs :: Scientific -> Scientific # signum :: Scientific -> Scientific # fromInteger :: Integer -> Scientific # | |
| Ord Scientific | Scientific numbers can be safely compared for ordering. No magnitude |
Defined in Data.Scientific Methods compare :: Scientific -> Scientific -> Ordering # (<) :: Scientific -> Scientific -> Bool # (<=) :: Scientific -> Scientific -> Bool # (>) :: Scientific -> Scientific -> Bool # (>=) :: Scientific -> Scientific -> Bool # max :: Scientific -> Scientific -> Scientific # min :: Scientific -> Scientific -> Scientific # | |
| Read Scientific | Supports the skipping of parentheses and whitespaces. Example: > read " ( (( -1.0e+3 ) ))" :: Scientific -1000.0 (Note: This |
Defined in Data.Scientific Methods readsPrec :: Int -> ReadS Scientific # readList :: ReadS [Scientific] # readPrec :: ReadPrec Scientific # readListPrec :: ReadPrec [Scientific] # | |
| Real Scientific | WARNING: Avoid applying |
Defined in Data.Scientific Methods toRational :: Scientific -> Rational # | |
| RealFrac Scientific | WARNING: the methods of the |
Defined in Data.Scientific Methods properFraction :: Integral b => Scientific -> (b, Scientific) # truncate :: Integral b => Scientific -> b # round :: Integral b => Scientific -> b # ceiling :: Integral b => Scientific -> b # floor :: Integral b => Scientific -> b # | |
| Show Scientific | See |
Defined in Data.Scientific Methods showsPrec :: Int -> Scientific -> ShowS # show :: Scientific -> String # showList :: [Scientific] -> ShowS # | |
| Hashable Scientific | A hash can be safely calculated from a
|
Defined in Data.Scientific | |
| ToJSON Scientific | |
Defined in Data.Aeson.Types.ToJSON Methods toJSON :: Scientific -> Value # toEncoding :: Scientific -> Encoding # toJSONList :: [Scientific] -> Value # toEncodingList :: [Scientific] -> Encoding # | |
| ToJSONKey Scientific | |
Defined in Data.Aeson.Types.ToJSON | |
| FromJSON Scientific | |
Defined in Data.Aeson.Types.FromJSON | |
| Binary Scientific | Note that in the future I intend to change the type of the |
Defined in Data.Scientific | |
| NFData Scientific | |
Defined in Data.Scientific Methods rnf :: Scientific -> () # | |
| Lift Scientific | Since: scientific-0.3.7.0 |
Defined in Data.Scientific | |
A space efficient, packed, unboxed Unicode text type.
Instances
| Hashable Text | |
Defined in Data.Hashable.Class | |
| ToJSON Text | |
Defined in Data.Aeson.Types.ToJSON | |
| ToJSONKey Text | |
Defined in Data.Aeson.Types.ToJSON | |
| FromJSON Text | |
| FromJSONKey Text | |
Defined in Data.Aeson.Types.FromJSON | |
| Chunk Text | |
Defined in Data.Attoparsec.Internal.Types | |
| type State Text | |
Defined in Data.Attoparsec.Internal.Types | |
| type ChunkElem Text | |
Defined in Data.Attoparsec.Internal.Types | |
| type Item Text | |
A JSON value represented as a Haskell value.
Instances
| Eq Value | |
| Data Value | |
Defined in Data.Aeson.Types.Internal Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Value -> c Value # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Value # dataTypeOf :: Value -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Value) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Value) # gmapT :: (forall b. Data b => b -> b) -> Value -> Value # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r # gmapQ :: (forall d. Data d => d -> u) -> Value -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Value -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Value -> m Value # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value # | |
| Ord Value | The ordering is total, consistent with Since: aeson-1.5.2.0 |
| Read Value | |
| Show Value | Since version 1.5.6.0 version object values are printed in lexicographic key order
|
| IsString Value | |
Defined in Data.Aeson.Types.Internal Methods fromString :: String -> Value # | |
| Generic Value | |
| Function Value | Since: aeson-2.0.3.0 |
| Arbitrary Value | Since: aeson-2.0.3.0 |
| CoArbitrary Value | Since: aeson-2.0.3.0 |
Defined in Data.Aeson.Types.Internal Methods coarbitrary :: Value -> Gen b -> Gen b # | |
| Hashable Value | |
Defined in Data.Aeson.Types.Internal | |
| ToJSON Value | |
Defined in Data.Aeson.Types.ToJSON | |
| KeyValue Object | Constructs a singleton |
| KeyValue Pair | |
| FromJSON Value | |
| NFData Value | |
Defined in Data.Aeson.Types.Internal | |
| FromString Encoding | |
Defined in Data.Aeson.Types.ToJSON Methods fromString :: String -> Encoding | |
| FromString Value | |
Defined in Data.Aeson.Types.ToJSON Methods fromString :: String -> Value | |
| Lift Value | Since: aeson-0.11.0.0 |
| GToJSON' Encoding arity (U1 :: Type -> Type) | |
| GToJSON' Value arity (V1 :: Type -> Type) | |
| GToJSON' Value arity (U1 :: Type -> Type) | |
| ToJSON1 f => GToJSON' Encoding One (Rec1 f) | |
| ToJSON1 f => GToJSON' Value One (Rec1 f) | |
| ToJSON a => GToJSON' Encoding arity (K1 i a :: Type -> Type) | |
| (EncodeProduct arity a, EncodeProduct arity b) => GToJSON' Encoding arity (a :*: b) | |
| ToJSON a => GToJSON' Value arity (K1 i a :: Type -> Type) | |
| (WriteProduct arity a, WriteProduct arity b, ProductSize a, ProductSize b) => GToJSON' Value arity (a :*: b) | |
| (ToJSON1 f, GToJSON' Encoding One g) => GToJSON' Encoding One (f :.: g) | |
| (ToJSON1 f, GToJSON' Value One g) => GToJSON' Value One (f :.: g) | |
| FromPairs Value (DList Pair) | |
Defined in Data.Aeson.Types.ToJSON | |
| v ~ Value => KeyValuePair v (DList Pair) | |
Defined in Data.Aeson.Types.ToJSON | |
| (GToJSON' Encoding arity a, ConsToJSON Encoding arity a, Constructor c) => SumToJSON' TwoElemArray Encoding arity (C1 c a) | |
Defined in Data.Aeson.Types.ToJSON | |
| (GToJSON' Value arity a, ConsToJSON Value arity a, Constructor c) => SumToJSON' TwoElemArray Value arity (C1 c a) | |
Defined in Data.Aeson.Types.ToJSON | |
| type Rep Value | |
Defined in Data.Aeson.Types.Internal type Rep Value = D1 ('MetaData "Value" "Data.Aeson.Types.Internal" "aeson-2.0.3.0-HoBWSDM3qT941k5ljFeQlI" 'False) ((C1 ('MetaCons "Object" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Object)) :+: (C1 ('MetaCons "Array" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Array)) :+: C1 ('MetaCons "String" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Text)))) :+: (C1 ('MetaCons "Number" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Scientific)) :+: (C1 ('MetaCons "Bool" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Bool)) :+: C1 ('MetaCons "Null" 'PrefixI 'False) (U1 :: Type -> Type)))) | |
Boxed vectors, supporting efficient slicing.
Instances
| Monad Vector | |
| Functor Vector | |
| MonadFix Vector | Instance has same semantics as one for lists Since: vector-0.12.2.0 |
Defined in Data.Vector | |
| MonadFail Vector | Since: vector-0.12.1.0 |
Defined in Data.Vector | |
| Applicative Vector | |
| Foldable Vector | |
Defined in Data.Vector Methods fold :: Monoid m => Vector m -> m # foldMap :: Monoid m => (a -> m) -> Vector a -> m # foldMap' :: Monoid m => (a -> m) -> Vector a -> m # foldr :: (a -> b -> b) -> b -> Vector a -> b # foldr' :: (a -> b -> b) -> b -> Vector a -> b # foldl :: (b -> a -> b) -> b -> Vector a -> b # foldl' :: (b -> a -> b) -> b -> Vector a -> b # foldr1 :: (a -> a -> a) -> Vector a -> a # foldl1 :: (a -> a -> a) -> Vector a -> a # elem :: Eq a => a -> Vector a -> Bool # maximum :: Ord a => Vector a -> a # minimum :: Ord a => Vector a -> a # | |
| Traversable Vector | |
| ToJSON1 Vector | |
Defined in Data.Aeson.Types.ToJSON Methods liftToJSON :: (a -> Value) -> ([a] -> Value) -> Vector a -> Value # liftToJSONList :: (a -> Value) -> ([a] -> Value) -> [Vector a] -> Value # liftToEncoding :: (a -> Encoding) -> ([a] -> Encoding) -> Vector a -> Encoding # liftToEncodingList :: (a -> Encoding) -> ([a] -> Encoding) -> [Vector a] -> Encoding # | |
| FromJSON1 Vector | |
| Alternative Vector | |
| MonadPlus Vector | |
| Eq1 Vector | |
| Ord1 Vector | |
Defined in Data.Vector | |
| Read1 Vector | |
Defined in Data.Vector | |
| Show1 Vector | |
| MonadZip Vector | |
| NFData1 Vector | Since: vector-0.12.1.0 |
Defined in Data.Vector | |
| Vector Vector a | |
Defined in Data.Vector Methods basicUnsafeFreeze :: PrimMonad m => Mutable Vector (PrimState m) a -> m (Vector a) # basicUnsafeThaw :: PrimMonad m => Vector a -> m (Mutable Vector (PrimState m) a) # basicLength :: Vector a -> Int # basicUnsafeSlice :: Int -> Int -> Vector a -> Vector a # basicUnsafeIndexM :: Monad m => Vector a -> Int -> m a # basicUnsafeCopy :: PrimMonad m => Mutable Vector (PrimState m) a -> Vector a -> m () # | |
| IsList (Vector a) | |
| Eq a => Eq (Vector a) | |
| Data a => Data (Vector a) | |
Defined in Data.Vector Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Vector a -> c (Vector a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Vector a) # toConstr :: Vector a -> Constr # dataTypeOf :: Vector a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Vector a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Vector a)) # gmapT :: (forall b. Data b => b -> b) -> Vector a -> Vector a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Vector a -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Vector a -> r # gmapQ :: (forall d. Data d => d -> u) -> Vector a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Vector a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Vector a -> m (Vector a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Vector a -> m (Vector a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Vector a -> m (Vector a) # | |
| Ord a => Ord (Vector a) | |
Defined in Data.Vector | |
| Read a => Read (Vector a) | |
| Show a => Show (Vector a) | |
| Semigroup (Vector a) | |
| Monoid (Vector a) | |
| ToJSON a => ToJSON (Vector a) | |
Defined in Data.Aeson.Types.ToJSON | |
| FromJSON a => FromJSON (Vector a) | |
| NFData a => NFData (Vector a) | |
Defined in Data.Vector | |
| type Mutable Vector | |
Defined in Data.Vector | |
| type Item (Vector a) | |
Defined in Data.Vector | |
withObject :: String -> (Object -> Parser a) -> Value -> Parser a #
withObject name f valuef to the Object when value
is an Object and fails otherwise.
Error message example
withObject "MyType" f (String "oops") -- Error: "parsing MyType failed, expected Object, but encountered String"
(.:) :: FromJSON a => Object -> Key -> Parser a #
Retrieve the value associated with the given key of an Object.
The result is empty if the key is not present or the value cannot
be converted to the desired type.
This accessor is appropriate if the key and value must be present
in an object for it to be valid. If the key and value are
optional, use .:? instead.
(.:?) :: FromJSON a => Object -> Key -> Parser (Maybe a) #
Retrieve the value associated with the given key of an Object. The
result is Nothing if the key is not present or if its value is Null,
or empty if the value cannot be converted to the desired type.
This accessor is most useful if the key and value can be absent
from an object without affecting its validity. If the key and
value are mandatory, use .: instead.
(.!=) :: Parser (Maybe a) -> a -> Parser a #
Helper for use in combination with .:? to provide default
values for optional JSON object fields.
This combinator is most useful if the key and value can be absent
from an object without affecting its validity and we know a default
value to assign in that case. If the key and value are mandatory,
use .: instead.
Example usage:
v1 <- o.:?"opt_field_with_dfl" .!= "default_val" v2 <- o.:"mandatory_field" v3 <- o.:?"opt_field2"