Copyright	(c) Edward Kmett 2013-2014, (c) Paul Wilson 2012
License	BSD3
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	non-portable
Safe Haskell	Trustworthy
Language	Haskell98

Data.Aeson.Lens

Contents

Numbers
Primitive
Objects and Arrays
Decoding

Description

Synopsis

Numbers

class AsNumber t where Source

Minimal complete definition

Nothing

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 Text
AsNumber Value
AsNumber Text
AsNumber Primitive

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

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
AsPrimitive Primitive
AsNumber Primitive
Typeable * Primitive

class AsNumber t => AsPrimitive t where Source

Minimal complete definition

Nothing

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

>>> "{\"a\": \"xyz\", \"b\": true}" ^? key "a" . _String
Just "xyz"

>>> "{\"a\": \"xyz\", \"b\": true}" ^? key "b" . _String
Nothing

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

_Bool :: Prism' t Bool Source

>>> "{\"a\": \"xyz\", \"b\": true}" ^? key "b" . _Bool
Just True

>>> "{\"a\": \"xyz\", \"b\": true}" ^? key "a" . _Bool
Nothing

>>> _Bool # True
"true"

>>> _Bool # False
"false"

_Null :: Prism' t () Source

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

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

>>> _Null # ()
"null"

Instances

AsPrimitive String
AsPrimitive ByteString
AsPrimitive ByteString
AsPrimitive Text
AsPrimitive Value
AsPrimitive Text
AsPrimitive Primitive

Objects and Arrays

class AsPrimitive t => AsValue t where Source

Minimal complete definition

Nothing

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 Text
AsValue Value
AsValue Text

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

An indexed Traversal into Object properties

>>> "{\"a\": 4, \"b\": 7}" ^@.. members
[("a",Number 4.0),("b",Number 7.0)]

>>> "{\"a\": 4, \"b\": 7}" & members . _Number *~ 10
"{\"a\":40,\"b\":70}"

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 where Source

Minimal complete definition

Nothing

Methods

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

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

Instances

AsJSON String
AsJSON ByteString
AsJSON ByteString
AsJSON Text
AsJSON Value
AsJSON Text