Portability	non-portable
Stability	experimental
Maintainer	Edward Kmett <ekmett@gmail.com>
Safe Haskell	Trustworthy

Data.Aeson.Lens

Contents

Numbers
Primitive
Objects and Arrays
Decoding

Description

Synopsis

Numbers

class AsNumber t whereSource

Methods

_Number :: Prism' t Scientific Source

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

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

_Double :: Prism' t Double Source

Prism into an Double over a Value, Primitive or Scientific

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

_Integer :: Prism' t Integer Source

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 aSource

Access Integer Values as Integrals.

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

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

nonNull :: Prism' Value Value Source

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 Source

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 whereSource

Methods

_Primitive :: Prism' t Primitive Source

>>> "[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 Source

_Bool :: Prism' t Bool Source

_Null :: Prism' t ()Source

Instances

AsPrimitive String
AsPrimitive ByteString
AsPrimitive ByteString
AsPrimitive Value
AsPrimitive Primitive

Objects and Arrays

class AsPrimitive t => AsValue t whereSource

Methods

_Value :: Prism' t Value Source

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

_Object :: Prism' t (HashMap Text Value)Source

>>> "{\"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)Source

>>> "[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 Source

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 Source

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

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 Source

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 whereSource

Methods

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

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

Instances

AsJSON String
AsJSON ByteString
AsJSON ByteString
AsJSON Value