Copyright	(c) Edward Kmett 2013-2019 (c) Paul Wilson 2012
License	BSD3
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	non-portable
Safe Haskell	Trustworthy
Language	Haskell2010

Data.Aeson.Lens

Contents

Numbers
Objects and Arrays
Decoding
Pattern Synonyms
Orphan instances

Description

This module also exports orphan Ixed Value and Plated Value instances.

Synopsis

class AsNumber t where
- _Number :: Prism' t Scientific
- _Double :: Prism' t Double
- _Integer :: Prism' t Integer
_Integral :: (AsNumber t, Integral a) => Prism' t a
nonNull :: Prism' Value Value
class AsNumber t => AsValue t where
- _Value :: Prism' t Value
- _String :: Prism' t Text
- _Bool :: Prism' t Bool
- _Null :: Prism' t ()
- _Object :: Prism' t (KeyMap Value)
- _Array :: Prism' t (Vector Value)
key :: AsValue t => Key -> Traversal' t Value
atKey :: AsValue t => Key -> Traversal' t (Maybe Value)
members :: AsValue t => IndexedTraversal' Key t Value
nth :: AsValue t => Int -> Traversal' t Value
values :: AsValue t => IndexedTraversal' Int t Value
class IsKey t where
- _Key :: Iso' t Key
class AsJSON t where
- _JSON :: (FromJSON a, ToJSON b) => Prism t t a b
_JSON' :: (AsJSON t, FromJSON a, ToJSON a) => Prism' t a
pattern JSON :: (FromJSON a, ToJSON a, AsJSON t) => a -> t
pattern Value_ :: (FromJSON a, ToJSON a) => a -> Value
pattern Number_ :: AsNumber t => Scientific -> t
pattern Double :: AsNumber t => Double -> t
pattern Integer :: AsNumber t => Integer -> t
pattern Integral :: (AsNumber t, Integral a) => a -> t
pattern Bool_ :: AsValue t => Bool -> t
pattern String_ :: AsValue t => Text -> t
pattern Null_ :: AsValue t => t
pattern Key_ :: IsKey t => Key -> t

Numbers

class AsNumber t where #

Minimal complete definition

Nothing

Methods

_Number :: Prism' t Scientific #

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

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

default _Number :: AsValue t => Prism' t Scientific #

_Double :: Prism' t Double #

Prism into an Double over a Value or Scientific

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

_Integer :: Prism' t Integer #

Prism into an Integer over a Value or Scientific

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

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

>>> "42" ^? _Integer
Just 42

Instances

Instances details

AsNumber Value #
Instance details Defined in Data.Aeson.Lens Methods _Number :: Prism' Value Scientific # _Double :: Prism' Value Double # _Integer :: Prism' Value Integer #
AsNumber ByteString #
Instance details Defined in Data.Aeson.Lens Methods _Number :: Prism' ByteString Scientific # _Double :: Prism' ByteString Double # _Integer :: Prism' ByteString Integer #
AsNumber ByteString #
Instance details Defined in Data.Aeson.Lens Methods _Number :: Prism' ByteString Scientific # _Double :: Prism' ByteString Double # _Integer :: Prism' ByteString Integer #
AsNumber Scientific #
Instance details Defined in Data.Aeson.Lens Methods _Number :: Prism' Scientific Scientific # _Double :: Prism' Scientific Double # _Integer :: Prism' Scientific Integer #
AsNumber Text #
Instance details Defined in Data.Aeson.Lens Methods _Number :: Prism' Text Scientific # _Double :: Prism' Text Double # _Integer :: Prism' Text Integer #
AsNumber Text #
Instance details Defined in Data.Aeson.Lens Methods _Number :: Prism' Text Scientific # _Double :: Prism' Text Double # _Integer :: Prism' Text Integer #
AsNumber String #
Instance details Defined in Data.Aeson.Lens Methods _Number :: Prism' String Scientific # _Double :: Prism' String Double # _Integer :: Prism' String Integer #

_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

Objects and Arrays

class AsNumber t => AsValue t where #

Minimal complete definition

_Value

Methods

_Value :: Prism' t Value #

>>> preview _Value "[1,2,3]" == Just (Array (Vector.fromList [Number 1.0,Number 2.0,Number 3.0]))
True

_String :: Prism' t Text #

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

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

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

_Bool :: Prism' t Bool #

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

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

>>> _Bool # True :: String
"true"

>>> _Bool # False :: String
"false"

_Null :: Prism' t () #

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

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

>>> _Null # () :: String
"null"

_Object :: Prism' t (KeyMap Value) #

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

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

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

_Array :: Prism' t (Vector Value) #

>>> preview _Array "[1,2,3]" == Just (Vector.fromList [Number 1.0,Number 2.0,Number 3.0])
True

Instances

Instances details

AsValue Value #
Instance details Defined in Data.Aeson.Lens Methods _Value :: Prism' Value Value # _String :: Prism' Value Text # _Bool :: Prism' Value Bool # _Null :: Prism' Value () # _Object :: Prism' Value (KeyMap Value) # _Array :: Prism' Value (Vector Value) #
AsValue ByteString #
Instance details Defined in Data.Aeson.Lens Methods _Value :: Prism' ByteString Value # _String :: Prism' ByteString Text # _Bool :: Prism' ByteString Bool # _Null :: Prism' ByteString () # _Object :: Prism' ByteString (KeyMap Value) # _Array :: Prism' ByteString (Vector Value) #
AsValue ByteString #
Instance details Defined in Data.Aeson.Lens Methods _Value :: Prism' ByteString Value # _String :: Prism' ByteString Text # _Bool :: Prism' ByteString Bool # _Null :: Prism' ByteString () # _Object :: Prism' ByteString (KeyMap Value) # _Array :: Prism' ByteString (Vector Value) #
AsValue Text #
Instance details Defined in Data.Aeson.Lens Methods _Value :: Prism' Text Value # _String :: Prism' Text Text # _Bool :: Prism' Text Bool # _Null :: Prism' Text () # _Object :: Prism' Text (KeyMap Value) # _Array :: Prism' Text (Vector Value) #
AsValue Text #
Instance details Defined in Data.Aeson.Lens Methods _Value :: Prism' Text Value # _String :: Prism' Text Text # _Bool :: Prism' Text Bool # _Null :: Prism' Text () # _Object :: Prism' Text (KeyMap Value) # _Array :: Prism' Text (Vector Value) #
AsValue String #
Instance details Defined in Data.Aeson.Lens Methods _Value :: Prism' String Value # _String :: Prism' String Text # _Bool :: Prism' String Bool # _Null :: Prism' String () # _Object :: Prism' String (KeyMap Value) # _Array :: Prism' String (Vector Value) #

key :: AsValue t => Key -> Traversal' t Value #

Like ix, but for Object with Key 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

atKey :: AsValue t => Key -> Traversal' t (Maybe Value) #

Like key, but uses at instead of ix. This is handy when adding and removing object keys:

>>> "{\"a\": 100, \"b\": 200}" & atKey "a" .~ Nothing
"{\"b\":200}"

>>> "{\"a\": 100, \"b\": 200}" & atKey "c" ?~ String "300"
"{\"a\":100,\"b\":200,\"c\":\"300\"}"

members :: AsValue t => IndexedTraversal' Key t Value #

An indexed Traversal into Object properties

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

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

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]"

class IsKey t where #

Methods

_Key :: Iso' t Key #

_Key is an Iso from something to a Key. This is primarily intended for situations where one wishes to use object keys that are not string literals and therefore must be converted:

>>> let k = "a" :: Text
>>> "{\"a\": 100, \"b\": 200}" ^? key (k ^. _Key)
Just (Number 100.0)

Note that applying _Key directly to a string literal (e.g., "a" ^. _Key) will likely not typecheck when OverloadedStrings is enabled.

Instances

Instances details

IsKey Key #
Instance details Defined in Data.Aeson.Lens Methods _Key :: Iso' Key Key #
IsKey ByteString #	This instance assumes that you are dealing with UTF-8–encoded `ByteString`s, as this is the encoding that RFC 8259 requires JSON values to use. As such, this is not a full `Iso`, since non–UTF-8–encoded `ByteString`s will not roundtrip: `>>>` `let str = view _Key ("\255" :: Strict.ByteString)``>>>` `str`"\65533" `>>>` `view (from _Key) str :: Strict.ByteString`"\239\191\189"
Instance details Defined in Data.Aeson.Lens Methods _Key :: Iso' ByteString Key #
IsKey ByteString #	This instance assumes that you are dealing with UTF-8–encoded `ByteString`s, as this is the encoding that RFC 8259 requires JSON values to use. As such, this is not a full `Iso`, since non–UTF-8–encoded `ByteString`s will not roundtrip: `>>>` `let str = view _Key ("\255" :: Lazy.ByteString)``>>>` `str`"\65533" `>>>` `view (from _Key) str :: Lazy.ByteString`"\239\191\189"
Instance details Defined in Data.Aeson.Lens Methods _Key :: Iso' ByteString Key #
IsKey Text #
Instance details Defined in Data.Aeson.Lens Methods _Key :: Iso' Text Key #
IsKey Text #
Instance details Defined in Data.Aeson.Lens Methods _Key :: Iso' Text Key #
IsKey ShortText #
Instance details Defined in Data.Aeson.Lens Methods _Key :: Iso' ShortText Key #
IsKey String #
Instance details Defined in Data.Aeson.Lens Methods _Key :: Iso' String Key #

Decoding

class AsJSON t where #

Methods

_JSON :: (FromJSON a, ToJSON b) => Prism t t a b #

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

Instances

Instances details

AsJSON Value #
Instance details Defined in Data.Aeson.Lens Methods _JSON :: (FromJSON a, ToJSON b) => Prism Value Value a b #
AsJSON ByteString #
Instance details Defined in Data.Aeson.Lens Methods _JSON :: (FromJSON a, ToJSON b) => Prism ByteString ByteString a b #
AsJSON ByteString #
Instance details Defined in Data.Aeson.Lens Methods _JSON :: (FromJSON a, ToJSON b) => Prism ByteString ByteString a b #
AsJSON Text #
Instance details Defined in Data.Aeson.Lens Methods _JSON :: (FromJSON a, ToJSON b) => Prism Text Text a b #
AsJSON Text #
Instance details Defined in Data.Aeson.Lens Methods _JSON :: (FromJSON a, ToJSON b) => Prism Text Text a b #
AsJSON String #
Instance details Defined in Data.Aeson.Lens Methods _JSON :: (FromJSON a, ToJSON b) => Prism String String a b #