Data.Aeson.Lens

Numbers

class AsNumber t where

Methods

_Number :: Prism' t Scientific

>>> "[1, \"x\"]" ^? nth 0 . _Number
Just 1.0

>>> "[1, \"x\"]" ^? nth 1 . _Number
Nothing

_Double :: Prism' t Double

Prism into an Double over a Value, Primitive or Scientific

>>> "[10.2]" ^? nth 0 . _Double
Just 10.2

_Integer :: Prism' t Integer

Prism into an Integer over a Value, Primitive or Scientific

>>> "[10]" ^? nth 0 . _Integer
Just 10

>>> "[10.5]" ^? nth 0 . _Integer
Just 10

>>> "42" ^? _Integer
Just 42

Instances

AsNumber String

AsNumber ByteString

AsNumber ByteString

AsNumber Scientific

AsNumber Value

AsNumber Primitive

_Integral :: (AsNumber t, Integral a) => Prism' t a

Access Integer Values as Integrals.

>>> "[10]" ^? nth 0 . _Integral
Just 10

>>> "[10.5]" ^? nth 0 . _Integral
Just 10

nonNull :: Prism' Value Value

Prism into non-Null values

>>> "{\"a\": \"xyz\", \"b\": null}" ^? key "a" . nonNull
Just (String "xyz")

>>> "{\"a\": {}, \"b\": null}" ^? key "a" . nonNull
Just (Object (fromList []))

>>> "{\"a\": \"xyz\", \"b\": null}" ^? key "b" . nonNull
Nothing

Primitive

data Primitive

Primitives of Value

Constructors

StringPrim !Text

NumberPrim !Scientific

BoolPrim !Bool

NullPrim

Instances

Eq Primitive

Data Primitive

Ord Primitive

Show Primitive

Typeable Primitive

AsPrimitive Primitive

AsNumber Primitive

class AsNumber t => AsPrimitive t where

Methods

_Primitive :: Prism' t Primitive

>>> "[1, \"x\", null, true, false]" ^? nth 0 . _Primitive
Just (NumberPrim 1.0)

>>> "[1, \"x\", null, true, false]" ^? nth 1 . _Primitive
Just (StringPrim "x")

>>> "[1, \"x\", null, true, false]" ^? nth 2 . _Primitive
Just NullPrim

>>> "[1, \"x\", null, true, false]" ^? nth 3 . _Primitive
Just (BoolPrim True)

>>> "[1, \"x\", null, true, false]" ^? nth 4 . _Primitive
Just (BoolPrim False)

_String :: Prism' t Text

_Bool :: Prism' t Bool

_Null :: Prism' t ()

Instances

AsPrimitive String

AsPrimitive ByteString

AsPrimitive ByteString

AsPrimitive Value

AsPrimitive Primitive

Objects and Arrays

class AsPrimitive t => AsValue t where

Methods

_Value :: Prism' t Value

>>> "[1,2,3]" ^? _Value
Just (Array (fromList [Number 1.0,Number 2.0,Number 3.0]))

_Object :: Prism' t (HashMap Text Value)

>>> "{\"a\": {}, \"b\": null}" ^? key "a" . _Object
Just (fromList [])

>>> "{\"a\": {}, \"b\": null}" ^? key "b" . _Object
Nothing

>>> _Object._Wrapped # [("key" :: Text, _String # "value")] :: String
"{\"key\":\"value\"}"

_Array :: Prism' t (Vector Value)

>>> "[1,2,3]" ^? _Array
Just (fromList [Number 1.0,Number 2.0,Number 3.0])

Instances

AsValue String

AsValue ByteString

AsValue ByteString

AsValue Value

key :: AsValue t => Text -> Traversal' t Value

Like ix, but for Object with Text indices. This often has better inference than ix when used with OverloadedStrings.

>>> "{\"a\": 100, \"b\": 200}" ^? key "a"
Just (Number 100.0)

>>> "[1,2,3]" ^? key "a"
Nothing

members :: AsValue t => IndexedTraversal' Text t Value

nth :: AsValue t => Int -> Traversal' t Value

Like ix, but for Arrays with Int indexes

>>> "[1,2,3]" ^? nth 1
Just (Number 2.0)

>>> "\"a\": 100, \"b\": 200}" ^? nth 1
Nothing

>>> "[1,2,3]" & nth 1 .~ Number 20
"[1,20,3]"

values :: AsValue t => IndexedTraversal' Int t Value

An indexed Traversal into Array elements

>>> "[1,2,3]" ^.. values
[Number 1.0,Number 2.0,Number 3.0]

>>> "[1,2,3]" & values . _Number *~ 10
"[10,20,30]"

Decoding

class AsJSON t where

Methods

_JSON :: (FromJSON a, ToJSON a) => Prism' t a

_JSON is a Prism from something containing JSON to something encoded in that structure

Instances

AsJSON String

AsJSON ByteString

AsJSON ByteString

AsJSON Value