Lens.Micro.Aeson

Traversals for Data.Aeson, based on microlens for minimal dependencies.

For basic manipulation of Aeson values, full Prism functionality isn't necessary. Since all Prisms are inherently Traversals, we provide Traversals that mimic the behaviour of the Prisms found in the original Data.Aeson.Lens.

Numbers

class AsNumber t where

Traverse into various number types.

Minimal complete definition

Nothing

Methods

_Number :: Traversal' t Scientific

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

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

default _Number :: AsValue t => Traversal' t Scientific

_Double :: Traversal' t Double

Traversal into an Double over a Value or Scientific

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

_Integer :: Traversal' t Integer

Traversal 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

AsNumber String

Defined in Lens.Micro.Aeson

Methods

_Number :: Traversal' String Scientific

_Double :: Traversal' String Double

_Integer :: Traversal' String Integer

AsNumber ByteString

Defined in Lens.Micro.Aeson

Methods

_Number :: Traversal' ByteString Scientific

_Double :: Traversal' ByteString Double

_Integer :: Traversal' ByteString Integer

AsNumber ByteString

Defined in Lens.Micro.Aeson

Methods

_Number :: Traversal' ByteString Scientific

_Double :: Traversal' ByteString Double

_Integer :: Traversal' ByteString Integer

AsNumber Scientific

Defined in Lens.Micro.Aeson

Methods

_Number :: Traversal' Scientific Scientific

_Double :: Traversal' Scientific Double

_Integer :: Traversal' Scientific Integer

AsNumber Text

Defined in Lens.Micro.Aeson

Methods

_Number :: Traversal' Text Scientific

_Double :: Traversal' Text Double

_Integer :: Traversal' Text Integer

AsNumber Value

Defined in Lens.Micro.Aeson

Methods

_Number :: Traversal' Value Scientific

_Double :: Traversal' Value Double

_Integer :: Traversal' Value Integer

AsNumber Text

Defined in Lens.Micro.Aeson

Methods

_Number :: Traversal' Text Scientific

_Double :: Traversal' Text Double

_Integer :: Traversal' Text Integer

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

Access Integer Values as Integrals.

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

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

nonNull :: Traversal' Value Value

Traversal 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

Traverse into JSON Objects and Arrays.

Minimal complete definition

_Value

Methods

_Value :: Traversal' t Value

Traverse into data that encodes a Value

_String :: Traversal' t Text

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

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

_Bool :: Traversal' t Bool

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

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

_Null :: Traversal' t ()

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

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

_Object :: Traversal' t (KeyMap Value)

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

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

_Array :: Traversal' t (Vector Value)

Instances

AsValue String

Defined in Lens.Micro.Aeson

Methods

_Value :: Traversal' String Value

_String :: Traversal' String Text

_Bool :: Traversal' String Bool

_Null :: Traversal' String ()

_Object :: Traversal' String (KeyMap Value)

_Array :: Traversal' String (Vector Value)

AsValue ByteString

Defined in Lens.Micro.Aeson

Methods

_Value :: Traversal' ByteString Value

_String :: Traversal' ByteString Text

_Bool :: Traversal' ByteString Bool

_Null :: Traversal' ByteString ()

_Object :: Traversal' ByteString (KeyMap Value)

_Array :: Traversal' ByteString (Vector Value)

AsValue ByteString

Defined in Lens.Micro.Aeson

Methods

_Value :: Traversal' ByteString Value

_String :: Traversal' ByteString Text

_Bool :: Traversal' ByteString Bool

_Null :: Traversal' ByteString ()

_Object :: Traversal' ByteString (KeyMap Value)

_Array :: Traversal' ByteString (Vector Value)

AsValue Text

Defined in Lens.Micro.Aeson

Methods

_Value :: Traversal' Text Value

_String :: Traversal' Text Text

_Bool :: Traversal' Text Bool

_Null :: Traversal' Text ()

_Object :: Traversal' Text (KeyMap Value)

_Array :: Traversal' Text (Vector Value)

AsValue Value

Defined in Lens.Micro.Aeson

Methods

_Value :: Traversal' Value Value

_String :: Traversal' Value Text

_Bool :: Traversal' Value Bool

_Null :: Traversal' Value ()

_Object :: Traversal' Value (KeyMap Value)

_Array :: Traversal' Value (Vector Value)

AsValue Text

Defined in Lens.Micro.Aeson

Methods

_Value :: Traversal' Text Value

_String :: Traversal' Text Text0

_Bool :: Traversal' Text Bool

_Null :: Traversal' Text ()

_Object :: Traversal' Text (KeyMap Value)

_Array :: Traversal' Text (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

members :: AsValue t => Traversal' t Value

A Traversal into Object properties

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

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

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 => Traversal' t Value

A 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

Traverse into actual encoded JSON.

Methods

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

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

Instances

AsJSON String

Defined in Lens.Micro.Aeson

Methods

_JSON :: (FromJSON a, ToJSON a) => Traversal' String a

AsJSON ByteString

Defined in Lens.Micro.Aeson

Methods

_JSON :: (FromJSON a, ToJSON a) => Traversal' ByteString a

AsJSON ByteString

Defined in Lens.Micro.Aeson

Methods

_JSON :: (FromJSON a, ToJSON a) => Traversal' ByteString a

AsJSON Text

Defined in Lens.Micro.Aeson

Methods

_JSON :: (FromJSON a, ToJSON a) => Traversal' Text a

AsJSON Value

Defined in Lens.Micro.Aeson

Methods

_JSON :: (FromJSON a, ToJSON a) => Traversal' Value a

AsJSON Text

Defined in Lens.Micro.Aeson

Methods

_JSON :: (FromJSON a, ToJSON a) => Traversal' Text a