Std.Data.JSON.Value

This module provides definition and parsers for JSON Values, a Haskell JSON representation. The parsers is designed to comply with rfc8258, notable pitfalls are:

• The numeric representation use Scientific, which impose a limit on number's exponent part(limited to Int).
• Unescaped control characters(<=0x1F) are NOT accepted, (different from aeson).
• Only 0x20, 0x09, 0x0A, 0x0D are valid JSON whitespaces, skipSpaces from this module is different from skipSpaces.
• A JSON document shouldn't have trailing characters except whitespaces describe above, see parseValue' and parseValueChunks'.
• Objects are represented as key-value vectors, key order and duplicated keys are preserved for further processing.

Note that rfc8258 doesn't enforce unique key in objects, it's up to users to decided how to deal with key duplication, e.g. prefer first or last key, see withFlatMap or withFlatMapR for example.

There's no lazy parsers here, every pieces of JSON document will be parsed into a normal form Value. Object and Arrays payloads are packed into Vectors to avoid accumulating lists in memory. Read more about why no lazy parsing is needed.

Value type

data Value

A JSON value represented as a Haskell value.

The Object's payload is a key-value vector instead of a map, which parsed directly from JSON document. This design choice has following advantages:

• Allow different strategies handling duplicated keys.
• Allow different Map type to do further parsing, e.g. FlatMap
• Roundtrip without touching the original key-value order.
• Save time if constructing map is not neccessary, e.g. using a linear scan to find a key if only that key is needed.

Constructors

Object !(Vector (Text, Value))

Array !(Vector Value)

String !Text

Number !Scientific

Bool !Bool

Null

Instances

Eq Value

Defined in Std.Data.JSON.Value

Methods

(==) :: Value -> Value -> Bool

(/=) :: Value -> Value -> Bool

Show Value

Defined in Std.Data.JSON.Value

Methods

showsPrec :: Int -> Value -> ShowS

show :: Value -> String

showList :: [Value] -> ShowS

Generic Value

Defined in Std.Data.JSON.Value

Associated Types

type Rep Value :: Type -> Type

Methods

from :: Value -> Rep Value x

to :: Rep Value x -> Value

NFData Value

Defined in Std.Data.JSON.Value

Methods

rnf :: Value -> ()

Arbitrary Value

Defined in Std.Data.JSON.Value

Methods

arbitrary :: Gen Value

shrink :: Value -> [Value]

ToText Value

Defined in Std.Data.JSON.Value

Methods

toTextBuilder :: Int -> Value -> TextBuilder ()

FromValue Value

Defined in Std.Data.JSON.Base

Methods

fromValue :: Value -> Converter Value

EncodeJSON Value

Defined in Std.Data.JSON.Base

Methods

encodeJSON :: Value -> Builder ()

ToValue Value

Defined in Std.Data.JSON.Base

Methods

toValue :: Value -> Value

type Rep Value

Defined in Std.Data.JSON.Value

type Rep Value = D1 (MetaData "Value" "Std.Data.JSON.Value" "stdio-0.2.0.0-5YmH16k3vlO7FAtmF9PgfB" False) ((C1 (MetaCons "Object" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) SourceUnpack SourceStrict DecidedStrict) (Rec0 (Vector (Text, Value)))) :+: (C1 (MetaCons "Array" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) SourceUnpack SourceStrict DecidedStrict) (Rec0 (Vector Value))) :+: C1 (MetaCons "String" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) SourceUnpack SourceStrict DecidedStrict) (Rec0 Text)))) :+: (C1 (MetaCons "Number" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) SourceUnpack SourceStrict DecidedStrict) (Rec0 Scientific)) :+: (C1 (MetaCons "Bool" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 Bool)) :+: C1 (MetaCons "Null" PrefixI False) (U1 :: Type -> Type))))

parse into JSON Value

parseValue :: Bytes -> (Bytes, Either ParseError Value)

Parse Value without consuming trailing bytes.

parseValue' :: Bytes -> Either ParseError Value

Parse Value, and consume all trailing JSON white spaces, if there're bytes left, parsing will fail.

parseValueChunks :: Monad m => m Bytes -> Bytes -> m (Bytes, Either ParseError Value)

Increamental parse Value without consuming trailing bytes.

parseValueChunks' :: Monad m => m Bytes -> Bytes -> m (Either ParseError Value)

Increamental parse Value and consume all trailing JSON white spaces, if there're bytes left, parsing will fail.

Value Parsers

value :: Parser Value

JSON Value parser.

object :: Parser (Vector (Text, Value))

parse json array with leading 123 .

array :: Parser (Vector Value)

parse json array with leading 91 .

string :: Parser Text

skipSpaces :: Parser ()

The only valid whitespace in a JSON document is space, newline, carriage pure, and tab.