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

_Double :: Traversal' t Double

Traversal into an Double over a Value, Primitive or Scientific

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

_Integer :: Traversal' t Integer

Traversal 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 Scientific

AsNumber ByteString

AsNumber Text

AsNumber Value

AsNumber Text

AsNumber Primitive

_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

Primitive

data Primitive

Primitives of Value

Constructors

StringPrim !Text

NumberPrim !Scientific

BoolPrim !Bool

NullPrim

Instances

Eq Primitive

Data Primitive

Ord Primitive

Show Primitive

AsPrimitive Primitive

AsNumber Primitive

class AsNumber t => AsPrimitive t where

Traverse into various JSON primatives.

Minimal complete definition

Nothing

Methods

_Primitive :: Traversal' 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 :: 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

Instances

AsPrimitive String

AsPrimitive ByteString

AsPrimitive ByteString

AsPrimitive Text

AsPrimitive Value

AsPrimitive Text

AsPrimitive Primitive

Objects and Arrays

class AsPrimitive t => AsValue t where

Traverse into JSON Objects and Arrays.

Minimal complete definition

Nothing

Methods

_Value :: Traversal' t Value

Traverse into data that encodes a Value

_Object :: Traversal' t (HashMap Text Value)

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

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

_Array :: Traversal' t (Vector Value)

Instances

AsValue String

AsValue ByteString

AsValue ByteString

AsValue Text

AsValue Value

AsValue Text

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 => 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.

Minimal complete definition

Nothing

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

AsJSON ByteString

AsJSON ByteString

AsJSON Text

AsJSON Value

AsJSON Text