json-0.9: Support for serialising Haskell to and from JSON

Copyright(c) Galois, Inc. 2007-2009
LicenseBSD3
MaintainerSigbjorn Finne <sof@galois.com>
Stabilityprovisional
Portabilityportable
Safe HaskellSafe-Inferred
LanguageHaskell98

Text.JSON

Contents

Description

 

Synopsis

JSON Types

data JSValue Source

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

Instances

Eq JSValue 
Ord JSValue 
Read JSValue 
Show JSValue 
JSON JSValue

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

Typeable * JSValue 

Serialization to and from JSValues

class JSON a where Source

The class of types serialisable to and from JSON

Minimal complete definition

readJSON, showJSON

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 Source

A type for parser results

Constructors

Ok a 
Error String 

encode :: JSON a => a -> String Source

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 Source

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 Source

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 Source

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 Source

Strings can be represented a little more efficiently in JSON

toJSString :: String -> JSString Source

Turn a Haskell string into a JSON string.

data JSObject e Source

As can association lists

Instances

Eq e => Eq (JSObject e) 
Ord e => Ord (JSObject e) 
Read e => Read (JSObject e) 
Show e => Show (JSObject e) 
JSON a => JSON (JSObject a) 
Typeable (* -> *) JSObject 

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

Make JSON object out of an association list.

resultToEither :: Result a -> Either String a Source

Map Results to Eithers

Serialization to and from Strings.

Reading JSON

readJSNull :: GetJSON JSValue Source

Read the JSON null type

readJSBool :: GetJSON JSValue Source

Read the JSON Bool type

readJSString :: GetJSON JSValue Source

Read the JSON String type

readJSRational :: GetJSON Rational Source

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

readJSArray :: GetJSON JSValue Source

Read a list in JSON format

readJSObject :: GetJSON JSValue Source

Read an object in JSON format

readJSValue :: GetJSON JSValue Source

Read one of several possible JS types

Writing JSON

showJSNull :: ShowS Source

Write the JSON null type

showJSBool :: Bool -> ShowS Source

Write the JSON Bool type

showJSArray :: [JSValue] -> ShowS Source

Show a list in JSON format

showJSRational :: Rational -> ShowS Source

Show a Rational in JSON format

showJSObject :: JSObject JSValue -> ShowS Source

Show an association list in JSON format

showJSValue :: JSValue -> ShowS Source

Show JSON values

Instance helpers

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

Pull a value out of a JSON object.

class JSKey a where Source

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

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

Encode an association list as JSObject value.

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

Decode a JSObject value into an association list.