Text.JSON

JSON Types

data JSValue

JSON values

The type to which we encode Haskell values. There's a set of primitives, and a couple of heterogenous collection types.

Objects:

An object structure is represented as a pair of curly brackets surrounding zero or more name/value pairs (or members). A name is a string. A single colon comes after each name, separating the name from the value. A single comma separates a value from a following name.

Arrays:

An array structure is represented as square brackets surrounding zero or more values (or elements). Elements are separated by commas.

Only valid JSON can be constructed this way

Constructors

JSNull

JSBool !Bool

JSRational Bool !Rational

JSString JSString

JSArray [JSValue]

JSObject (JSObject JSValue)

Instances

Eq JSValue

Ord JSValue

Read JSValue

Show JSValue

Typeable JSValue

JSON JSValue

To ensure we generate valid JSON, we map Haskell types to JSValue internally, then pretty print that.

Serialization to and from JSValues

class JSON a where

The class of types serialisable to and from JSON

Methods

readJSON :: JSValue -> Result a

showJSON :: a -> JSValue

readJSONs :: JSValue -> Result [a]

showJSONs :: [a] -> JSValue

Instances

JSON Bool

JSON Char

JSON Double

JSON Float

JSON Int

JSON Int8

JSON Int16

JSON Int32

JSON Int64

JSON Integer

JSON Ordering

JSON Word

JSON Word8

JSON Word16

JSON Word32

JSON Word64

JSON ()

JSON ByteString

JSON ByteString

JSON IntSet

JSON Text

JSON JSString

JSON JSValue

To ensure we generate valid JSON, we map Haskell types to JSValue internally, then pretty print that.

JSON a => JSON [a]

JSON a => JSON (Maybe a)

JSON a => JSON (IntMap a)

(Ord a, JSON a) => JSON (Set a)

JSON a => JSON (JSObject a)

(JSON a, JSON b) => JSON (Either a b)

(JSON a, JSON b) => JSON (a, b)

(Ix i, JSON i, JSON e) => JSON (Array i e)

(Ord a, JSON a, JSON b) => JSON (Map a b)

(JSON a, JSON b, JSON c) => JSON (a, b, c)

(JSON a, JSON b, JSON c, JSON d) => JSON (a, b, c, d)

Encoding and Decoding

data Result a

A type for parser results

Constructors

Ok a

Error String

Instances

Monad Result

Functor Result

MonadPlus Result

Applicative Result

Alternative Result

Eq a => Eq (Result a)

Show a => Show (Result a)

encode :: JSON a => a -> String

Encode a Haskell value into a string, in JSON format.

This is a superset of JSON, as types other than Array and Object are allowed at the top level.

decode :: JSON a => String -> Result a

Decode a String representing a JSON value (either an object, array, bool, number, null)

This is a superset of JSON, as types other than Array and Object are allowed at the top level.

encodeStrict :: JSON a => a -> String

Encode a value as a String in strict JSON format. This follows the spec, and requires all values at the top level to be wrapped in either an Array or Object. JSON types to be an Array or Object.

decodeStrict :: JSON a => String -> Result a

Decode a String representing a strict JSON value. This follows the spec, and requires top level JSON types to be an Array or Object.

Wrapper Types

data JSString

Strings can be represented a little more efficiently in JSON

Instances

Eq JSString

Ord JSString

Read JSString

Show JSString

Typeable JSString

JSKey JSString

JSON JSString

toJSString :: String -> JSString

Turn a Haskell string into a JSON string.

fromJSString :: JSString -> String

data JSObject e

As can association lists

Instances

Typeable1 JSObject

Eq e => Eq (JSObject e)

(Eq (JSObject e), Ord e) => Ord (JSObject e)

Read e => Read (JSObject e)

Show e => Show (JSObject e)

JSON a => JSON (JSObject a)

toJSObject :: [(String, a)] -> JSObject a

Make JSON object out of an association list.

fromJSObject :: JSObject e -> [(String, e)]

resultToEither :: Result a -> Either String a

Map Results to Eithers

Serialization to and from Strings.

Reading JSON

readJSNull :: GetJSON JSValue

Read the JSON null type

readJSBool :: GetJSON JSValue

Read the JSON Bool type

readJSString :: GetJSON JSValue

Read the JSON String type

readJSRational :: GetJSON Rational

Read an Integer or Double in JSON format, returning a Rational

readJSArray :: GetJSON JSValue

Read a list in JSON format

readJSObject :: GetJSON JSValue

Read an object in JSON format

readJSValue :: GetJSON JSValue

Read one of several possible JS types

Writing JSON

showJSNull :: ShowS

Write the JSON null type

showJSBool :: Bool -> ShowS

Write the JSON Bool type

showJSArray :: [JSValue] -> ShowS

Show a list in JSON format

showJSRational :: Rational -> ShowS

Show a Rational in JSON format

showJSRational' :: Bool -> Rational -> ShowS

showJSObject :: JSObject JSValue -> ShowS

Show an association list in JSON format

showJSValue :: JSValue -> ShowS

Show JSON values

Instance helpers

makeObj :: [(String, JSValue)] -> JSValue

valFromObj :: JSON a => String -> JSObject JSValue -> Result a

Pull a value out of a JSON object.

class JSKey a where

Haskell types that can be used as keys in JSON objects.

Methods

toJSKey :: a -> String

fromJSKey :: String -> Maybe a

Instances

JSKey Int

JSKey String

JSKey JSString

encJSDict :: (JSKey a, JSON b) => [(a, b)] -> JSValue

Encode an association list as JSObject value.

decJSDict :: (JSKey a, JSON b) => String -> JSValue -> Result [(a, b)]

Decode a JSObject value into an association list.