Z-Data-0.5.0.0: Array, vector and text
Copyright(c) Dong Han 2020
LicenseBSD
Maintainerwinterland1989@gmail.com
Stabilityexperimental
Portabilitynon-portable
Safe HaskellNone
LanguageHaskell2010

Z.Data.JSON

Description

Types and functions for working efficiently with JSON data, the design is quite similar to aeson or json:

  • Encode to bytes can be done directly via encodeJSON.
  • Decode are split in two step, first we parse JSON doc into Value, then convert to haskell data via fromValue.
  • ToValue are provided so that other doc formats can be easily supported, such as YAML.
Synopsis

How to use this module

This module is intended to be used qualified, e.g.

import qualified Z.Data.JSON as JSON
import           Z.Data.JSON ((.:), JSON(..))

The easiest way to use the library is to define target data type, deriving Generic and JSON instances, which provides:

For example,

{-# LANGUAGE DeriveGeneric, DeriveAnyClass, DerivingStrategies #-}

import GHC.Generics (Generic)
import qualified Z.Data.Builder as Builder
import qualified Z.Data.JSON as JSON
import qualified Z.Data.Text as T

data Person = Person {name :: T.Text, age :: Int}
    deriving (Show, Generic)
    deriving anyclass (JSON.JSON)

We can now encode & decode with Text like so:

>>> JSON.encodeText (Person{ name="Alice", age=16 })
"{\"age\":16,\"name\":\"Alice\"}"
>>> JSON.decodeText' "{\"age\":16,\"name\":\"Alice\"}" :: Either JSON.DecodeError Person
Right (Person {age = 16, name = "Alice"})

The Generic instances convert(encode) Haskell data with following rules:

  • Constructors without payloads are encoded as JSON String, data T = A | B are encoded as "A" or "B".
  • Single constructor are ingored if there're payloads, data T = T ..., T is ingored:
  • Records are encoded as JSON object. data T = T{k1 :: .., k2 :: ..} are encoded as {"k1":...,"k2":...}.
  • Plain product are encoded as JSON array. data T = T t1 t2 are encoded as "[x1,x2]".
  • Single field plain product are encoded as it is, i.e. data T = T t are encoded as "x" just like its payload.
  • Multiple constructors are convert to single key JSON object if there're payloads:
  • Records are encoded as JSON object like above. data T = A | B {k1 :: .., k2 :: ..} are encoded as {"B":{"k1":...,"k2":...}} in B .. .. case, or "A" in A case.
  • Plain product are similar to above, wrappered by an outer single-key object layer marking which constructor.

These rules apply to user defined ADTs, but some built-in instances have different behaviour, namely:

  • Maybe a are encoded as JSON null in Nothing case, or directly encoded to its payload in Just case.
  • [a] are encoded to JSON array, including [Char], i.e. there's no special treatment to String. To get JSON string, use Text.
  • NonEmpty, Vector, PrimVector, HashSet, FlatSet, FlatIntSet are also encoded to JSON array.
  • HashMap, FlatMap, FlatIntMap are encoded to JSON object.

There're some modifying options if you providing a custom Settings, which allow you to modify field name or constructor name, but please DO NOT produce control characters during your modification, since we assume field labels and constructor name won't contain them, thus we can save an extra escaping pass. To use custom Settings just write:

data T = T {fooT :: Int, barT :: [Int]} deriving Generic
instance JSON.ToValue T where
    -- You can omit following definition if you don't need to change settings
    toValue = JSON.gToValue JSON.defaultSettings{ JSON.fieldFmt = JSON.snakeCase } . from

-- define this instances if you need fast JSON encoding(without convert to JSON.Value first)
instance JSON.EncodeJSON T where
    -- You can omit following definition if you don't need to change settings
    encodeJSON = JSON.gEncodeJSON JSON.defaultSettings{ JSON.fieldFmt = JSON.snakeCase } . from
>>> JSON.toValue (T 0 [1,2,3])
Object [("foo_t",Number 0.0),("bar_t",Array [Number 1.0,Number 2.0,Number 3.0])]

You can write JSON instances by hand if the Generic based one doesn't suit you. Here is an example similar to aeson's.

import qualified Z.Data.Text          as T
import qualified Z.Data.Vector        as V
import qualified Z.Data.Builder       as B
import qualified Z.Data.JSON          as JSON
import           Z.Data.JSON          ((.:), (.=), (.!), JSON(..))

data Person = Person { name :: T.Text , age  :: Int } deriving Show

instance JSON Person where
    fromValue = JSON.withFlatMapR "Person" $ \ v -> Person
                    <$> v .: "name"
                    <*> v .: "age"

    toValue (Person n a) = JSON.object ["name" .= n, "age" .= a]

    encodeJSON (Person n a) = JSON.object' $ ("name" .! n <> "age" .! a)
>>> toValue (Person "Joe" 12)
Object [("name",String "Joe"),("age",Number 12.0)]
>>> JSON.convert' @Person . JSON.Object $ V.pack [("name",JSON.String "Joe"),("age",JSON.Number 12.0)]
Right (Person {name = "Joe", age = 12})
>>> JSON.encodeText (Person "Joe" 12)
"{"name":"Joe","age":12}"

The Value type is different from aeson's one in that we use Vector (Text, Value) to represent JSON objects, thus we can choose different strategies on key duplication, the lookup map type, etc. so instead of a single withObject, we provide withHashMap, withHashMapR, withFlatMap and withFlatMapR which use different lookup map type, and different key order piority. Most of time FlatMap is faster than HashMap since we only use the lookup map once, the cost of constructing a HashMap is higher. If you want to directly working on key-values, withKeyValues provide key-values vector access.

There're some useful tools to help write encoding code in Z.Data.JSON.Builder module, such as JSON string escaping tool, etc.

If you don't particularly care for fast encoding, you can also use toValue together with value builder, the overhead is usually very small.

JSON Class

class JSON a where Source #

Type class for encode & decode JSON.

Minimal complete definition

Nothing

Methods

fromValue :: Value -> Converter a Source #

default fromValue :: (Generic a, GFromValue (Rep a)) => Value -> Converter a Source #

toValue :: a -> Value Source #

default toValue :: (Generic a, GToValue (Rep a)) => a -> Value Source #

encodeJSON :: a -> Builder () Source #

default encodeJSON :: (Generic a, GEncodeJSON (Rep a)) => a -> Builder () Source #

Instances

Instances details
JSON Bool Source # 
Instance details

Defined in Z.Data.JSON.Base

JSON Char Source # 
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JSON Double Source # 
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JSON Float Source # 
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JSON Int Source # 
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JSON Int8 Source # 
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JSON Int16 Source # 
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JSON Int32 Source # 
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JSON Int64 Source # 
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JSON Integer Source #

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype Integer and provide your own instance using withScientific if you want to allow larger inputs.

Instance details

Defined in Z.Data.JSON.Base

JSON Natural Source #

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype Natural and provide your own instance using withScientific if you want to allow larger inputs.

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JSON Ordering Source # 
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JSON Word Source # 
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JSON Word8 Source # 
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JSON Word16 Source # 
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JSON Word32 Source # 
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JSON Word64 Source # 
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JSON () Source # 
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JSON Version Source #

Only round trip versionBranch as JSON array.

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JSON ExitCode Source # 
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JSON CChar Source # 
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JSON CSChar Source # 
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JSON CUChar Source # 
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JSON CShort Source # 
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JSON CUShort Source # 
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JSON CInt Source # 
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JSON CUInt Source # 
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JSON CLong Source # 
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JSON CULong Source # 
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JSON CLLong Source # 
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JSON CULLong Source # 
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JSON CBool Source # 
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JSON CFloat Source # 
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JSON CDouble Source # 
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JSON CPtrdiff Source # 
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JSON CSize Source # 
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JSON CWchar Source # 
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JSON CSigAtomic Source # 
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JSON CClock Source # 
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JSON CTime Source # 
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JSON CUSeconds Source # 
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JSON CSUSeconds Source # 
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JSON CIntPtr Source # 
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JSON CUIntPtr Source # 
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JSON CIntMax Source # 
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JSON CUIntMax Source # 
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JSON IntSet Source # 
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JSON ByteArray Source # 
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JSON Scientific Source #

Note this instance doesn't reject large input

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JSON ZonedTime Source #
YYYY-MM-DDTHH:MM:SS.SSSZ
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JSON LocalTime Source #
YYYY-MM-DDTHH:MM:SS.SSSZ
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JSON TimeOfDay Source #
HH:MM:SS.SSS
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JSON CalendarDiffTime Source # 
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JSON UTCTime Source #
YYYY-MM-DDTHH:MM:SS.SSSZ
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JSON SystemTime Source #

{"seconds": SSS, "nanoseconds": NNN}.

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JSON NominalDiffTime Source #

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype NominalDiffTime and provide your own instance using withScientific if you want to allow larger inputs.

Instance details

Defined in Z.Data.JSON.Base

JSON DiffTime Source #

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype DiffTime and provide your own instance using withScientific if you want to allow larger inputs.

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JSON DayOfWeek Source # 
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JSON Day Source #
YYYY-MM-DD
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JSON CalendarDiffDays Source # 
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JSON Text Source # 
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JSON FlatIntSet Source # 
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JSON Value Source # 
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JSON HexBytes Source # 
Instance details

Defined in Z.Data.Vector.Hex

JSON Base64Bytes Source # 
Instance details

Defined in Z.Data.Vector.Base64

JSON CBytes Source #

JSON instances check if CBytes is proper UTF8 encoded, if it is, decode/encode it as Text, otherwise as Bytes.

> encodeText ("hello" :: CBytes)
""hello""
> encodeText ("hello\NUL" :: CBytes)     -- \NUL is encoded as C0 80
"[104,101,108,108,111,192,128]"
Instance details

Defined in Z.Data.CBytes

JSON a => JSON [a] Source # 
Instance details

Defined in Z.Data.JSON.Base

Methods

fromValue :: Value -> Converter [a] Source #

toValue :: [a] -> Value Source #

encodeJSON :: [a] -> Builder () Source #

JSON a => JSON (Maybe a) Source # 
Instance details

Defined in Z.Data.JSON.Base

(JSON a, Integral a) => JSON (Ratio a) Source #

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype Ratio and provide your own instance using withScientific if you want to allow larger inputs.

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JSON a => JSON (Min a) Source # 
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JSON a => JSON (Max a) Source # 
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JSON a => JSON (First a) Source # 
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JSON a => JSON (Last a) Source # 
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JSON a => JSON (WrappedMonoid a) Source # 
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JSON a => JSON (Identity a) Source # 
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JSON a => JSON (First a) Source # 
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JSON a => JSON (Last a) Source # 
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JSON a => JSON (Dual a) Source # 
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JSON a => JSON (NonEmpty a) Source # 
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JSON a => JSON (IntMap a) Source # 
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JSON a => JSON (Tree a) Source # 
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JSON a => JSON (Seq a) Source # 
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(Ord a, JSON a) => JSON (Set a) Source # 
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(Prim a, JSON a) => JSON (PrimArray a) Source # 
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JSON a => JSON (SmallArray a) Source # 
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JSON a => JSON (Array a) Source # 
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(Eq a, Hashable a, JSON a) => JSON (HashSet a) Source # 
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(Prim a, JSON a) => JSON (PrimVector a) Source # 
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JSON a => JSON (Vector a) Source # 
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(Ord a, JSON a) => JSON (FlatSet a) Source # 
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JSON a => JSON (FlatIntMap a) Source # 
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(JSON a, JSON b) => JSON (Either a b) Source # 
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(JSON a, JSON b) => JSON (a, b) Source # 
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Defined in Z.Data.JSON.Base

Methods

fromValue :: Value -> Converter (a, b) Source #

toValue :: (a, b) -> Value Source #

encodeJSON :: (a, b) -> Builder () Source #

HasResolution a => JSON (Fixed a) Source #

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype Fixed and provide your own instance using withScientific if you want to allow larger inputs.

Instance details

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JSON (Proxy a) Source #

Use Null as Proxy a

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JSON a => JSON (Map Text a) Source # 
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JSON a => JSON (HashMap Text a) Source #

default instance prefer later key

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(PrimUnlifted a, JSON a) => JSON (UnliftedArray a) Source # 
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JSON a => JSON (FlatMap Text a) Source #

default instance prefer later key

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(JSON a, JSON b, JSON c) => JSON (a, b, c) Source # 
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Defined in Z.Data.JSON.Base

Methods

fromValue :: Value -> Converter (a, b, c) Source #

toValue :: (a, b, c) -> Value Source #

encodeJSON :: (a, b, c) -> Builder () Source #

JSON a => JSON (Const a b) Source # 
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JSON b => JSON (Tagged a b) Source # 
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(JSON a, JSON b, JSON c, JSON d) => JSON (a, b, c, d) Source # 
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Defined in Z.Data.JSON.Base

Methods

fromValue :: Value -> Converter (a, b, c, d) Source #

toValue :: (a, b, c, d) -> Value Source #

encodeJSON :: (a, b, c, d) -> Builder () Source #

(JSON (f a), JSON (g a)) => JSON (Product f g a) Source # 
Instance details

Defined in Z.Data.JSON.Base

(JSON (f a), JSON (g a), JSON a) => JSON (Sum f g a) Source # 
Instance details

Defined in Z.Data.JSON.Base

Methods

fromValue :: Value -> Converter (Sum f g a) Source #

toValue :: Sum f g a -> Value Source #

encodeJSON :: Sum f g a -> Builder () Source #

(JSON a, JSON b, JSON c, JSON d, JSON e) => JSON (a, b, c, d, e) Source # 
Instance details

Defined in Z.Data.JSON.Base

Methods

fromValue :: Value -> Converter (a, b, c, d, e) Source #

toValue :: (a, b, c, d, e) -> Value Source #

encodeJSON :: (a, b, c, d, e) -> Builder () Source #

JSON (f (g a)) => JSON (Compose f g a) Source # 
Instance details

Defined in Z.Data.JSON.Base

(JSON a, JSON b, JSON c, JSON d, JSON e, JSON f) => JSON (a, b, c, d, e, f) Source # 
Instance details

Defined in Z.Data.JSON.Base

Methods

fromValue :: Value -> Converter (a, b, c, d, e, f) Source #

toValue :: (a, b, c, d, e, f) -> Value Source #

encodeJSON :: (a, b, c, d, e, f) -> Builder () Source #

(JSON a, JSON b, JSON c, JSON d, JSON e, JSON f, JSON g) => JSON (a, b, c, d, e, f, g) Source # 
Instance details

Defined in Z.Data.JSON.Base

Methods

fromValue :: Value -> Converter (a, b, c, d, e, f, g) Source #

toValue :: (a, b, c, d, e, f, g) -> Value Source #

encodeJSON :: (a, b, c, d, e, f, g) -> Builder () Source #

data Value Source #

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.

Instances

Instances details
Eq Value Source # 
Instance details

Defined in Z.Data.JSON.Value

Methods

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

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

Ord Value Source # 
Instance details

Defined in Z.Data.JSON.Value

Methods

compare :: Value -> Value -> Ordering #

(<) :: Value -> Value -> Bool #

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

(>) :: Value -> Value -> Bool #

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

max :: Value -> Value -> Value #

min :: Value -> Value -> Value #

Show Value Source # 
Instance details

Defined in Z.Data.JSON.Value

Methods

showsPrec :: Int -> Value -> ShowS #

show :: Value -> String #

showList :: [Value] -> ShowS #

Generic Value Source # 
Instance details

Defined in Z.Data.JSON.Value

Associated Types

type Rep Value :: Type -> Type #

Methods

from :: Value -> Rep Value x #

to :: Rep Value x -> Value #

Arbitrary Value Source # 
Instance details

Defined in Z.Data.JSON.Value

Methods

arbitrary :: Gen Value #

shrink :: Value -> [Value] #

NFData Value Source # 
Instance details

Defined in Z.Data.JSON.Value

Methods

rnf :: Value -> () #

Print Value Source # 
Instance details

Defined in Z.Data.JSON.Value

Methods

toUTF8BuilderP :: Int -> Value -> Builder () Source #

JSON Value Source # 
Instance details

Defined in Z.Data.JSON.Base

type Rep Value Source # 
Instance details

Defined in Z.Data.JSON.Value

defaultSettings :: Settings Source #

Settings T.pack T.pack False

data Settings Source #

Generic encode/decode Settings

There should be no control characters in formatted texts since we don't escaping those field names or constructor names (defaultSettings relys on Haskell's lexical property). Otherwise encodeJSON will output illegal JSON string.

Constructors

Settings 

Fields

snakeCase :: String -> Text Source #

Snake casing a pascal cased constructor name or camel cased field name, words are always lower cased and separated by an underscore.

trainCase :: String -> Text Source #

Train casing a pascal cased constructor name or camel cased field name, words are always lower cased and separated by a hyphen.

Encode & Decode

decode :: JSON a => Bytes -> (Bytes, Either DecodeError a) Source #

Decode a JSON bytes, return any trailing bytes.

decode' :: JSON a => Bytes -> Either DecodeError a Source #

Decode a JSON doc, only trailing JSON whitespace are allowed.

decodeText :: JSON a => Text -> (Text, Either DecodeError a) Source #

Decode a JSON text, return any trailing text.

decodeText' :: JSON a => Text -> Either DecodeError a Source #

Decode a JSON doc, only trailing JSON whitespace are allowed.

type ParseChunks m chunk err x = m chunk -> chunk -> m (chunk, Either err x) Source #

Type alias for a streaming parser, draw chunk from Monad m (with a initial chunk), return result in Either err x.

decodeChunks :: (JSON a, Monad m) => ParseChunks m Bytes DecodeError a Source #

Decode JSON doc chunks, return trailing bytes.

encode :: JSON a => a -> Bytes Source #

Directly encode data to JSON bytes.

encodeChunks :: JSON a => a -> [Bytes] Source #

Encode data to JSON bytes chunks.

encodeText :: JSON a => a -> Text Source #

Text version encode.

parse into JSON Value

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

Parse Value without consuming trailing bytes.

parseValue' :: Bytes -> Either ParseError Value Source #

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) Source #

Increamental parse Value without consuming trailing bytes.

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

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

Generic functions

gToValue :: GToValue f => Settings -> f a -> Value Source #

gFromValue :: GFromValue f => Settings -> Value -> Converter (f a) Source #

gEncodeJSON :: GEncodeJSON f => Settings -> f a -> Builder () Source #

Convert Value to Haskell data

convertValue :: JSON a => Value -> Either ConvertError a Source #

Run a Converter with input value.

newtype Converter a Source #

Converter provides a monadic interface to convert protocol IR (e.g.Value) to Haskell ADT.

Constructors

Converter 

Fields

Instances

Instances details
Monad Converter Source # 
Instance details

Defined in Z.Data.JSON.Converter

Methods

(>>=) :: Converter a -> (a -> Converter b) -> Converter b #

(>>) :: Converter a -> Converter b -> Converter b #

return :: a -> Converter a #

Functor Converter Source # 
Instance details

Defined in Z.Data.JSON.Converter

Methods

fmap :: (a -> b) -> Converter a -> Converter b #

(<$) :: a -> Converter b -> Converter a #

MonadFail Converter Source # 
Instance details

Defined in Z.Data.JSON.Converter

Methods

fail :: String -> Converter a #

Applicative Converter Source # 
Instance details

Defined in Z.Data.JSON.Converter

Methods

pure :: a -> Converter a #

(<*>) :: Converter (a -> b) -> Converter a -> Converter b #

liftA2 :: (a -> b -> c) -> Converter a -> Converter b -> Converter c #

(*>) :: Converter a -> Converter b -> Converter b #

(<*) :: Converter a -> Converter b -> Converter a #

Alternative Converter Source # 
Instance details

Defined in Z.Data.JSON.Converter

Methods

empty :: Converter a #

(<|>) :: Converter a -> Converter a -> Converter a #

some :: Converter a -> Converter [a] #

many :: Converter a -> Converter [a] #

MonadPlus Converter Source # 
Instance details

Defined in Z.Data.JSON.Converter

Methods

mzero :: Converter a #

mplus :: Converter a -> Converter a -> Converter a #

fail' :: Text -> Converter a Source #

Text version of fail.

(<?>) :: Converter a -> PathElement -> Converter a infixl 9 Source #

Add (JSON) Path context to a converter

When converting a complex structure, it helps to annotate (sub)converters with context, so that if an error occurs, you can find its location.

withFlatMapR "Person" $ \o ->
  Person
    <$> o .: "name" <?> Key "name"
    <*> o .: "age" <?> Key "age"

(Standard methods like (.:) already do this.)

With such annotations, if an error occurs, you will get a (JSON) Path location of that error.

prependContext :: Text -> Converter a -> Converter a Source #

Add context to a failure message, indicating the name of the structure being converted.

prependContext "MyType" (fail "[error message]")
-- Error: "converting MyType failed, [error message]"

data PathElement Source #

Elements of a (JSON) Value path used to describe the location of an error.

Constructors

Key !Text

Path element of a key into an object, "object.key".

Index !Int

Path element of an index into an array, "array[index]".

Embedded

path of a embedded (JSON) String

Instances

Instances details
Eq PathElement Source # 
Instance details

Defined in Z.Data.JSON.Converter

Ord PathElement Source # 
Instance details

Defined in Z.Data.JSON.Converter

Show PathElement Source # 
Instance details

Defined in Z.Data.JSON.Converter

Generic PathElement Source # 
Instance details

Defined in Z.Data.JSON.Converter

Associated Types

type Rep PathElement :: Type -> Type #

NFData PathElement Source # 
Instance details

Defined in Z.Data.JSON.Converter

Methods

rnf :: PathElement -> () #

type Rep PathElement Source # 
Instance details

Defined in Z.Data.JSON.Converter

type Rep PathElement = D1 ('MetaData "PathElement" "Z.Data.JSON.Converter" "Z-Data-0.5.0.0-BfRSlUrinZc7kyLStIUBvV" 'False) (C1 ('MetaCons "Key" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'SourceUnpack 'SourceStrict 'DecidedStrict) (Rec0 Text)) :+: (C1 ('MetaCons "Index" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'SourceUnpack 'SourceStrict 'DecidedStrict) (Rec0 Int)) :+: C1 ('MetaCons "Embedded" 'PrefixI 'False) (U1 :: Type -> Type)))

data ConvertError Source #

Error info with (JSON) Path info.

Constructors

ConvertError 

Fields

Instances

Instances details
Eq ConvertError Source # 
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Defined in Z.Data.JSON.Converter

Ord ConvertError Source # 
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Defined in Z.Data.JSON.Converter

Show ConvertError Source # 
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Defined in Z.Data.JSON.Converter

Generic ConvertError Source # 
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Defined in Z.Data.JSON.Converter

Associated Types

type Rep ConvertError :: Type -> Type #

NFData ConvertError Source # 
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Defined in Z.Data.JSON.Converter

Methods

rnf :: ConvertError -> () #

Print ConvertError Source # 
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Defined in Z.Data.JSON.Converter

type Rep ConvertError Source # 
Instance details

Defined in Z.Data.JSON.Converter

type Rep ConvertError = D1 ('MetaData "ConvertError" "Z.Data.JSON.Converter" "Z-Data-0.5.0.0-BfRSlUrinZc7kyLStIUBvV" 'False) (C1 ('MetaCons "ConvertError" 'PrefixI 'True) (S1 ('MetaSel ('Just "errPath") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 [PathElement]) :*: S1 ('MetaSel ('Just "errMsg") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Text)))

typeMismatch Source #

Arguments

:: Text

The name of the type you are trying to convert.

-> Text

The JSON value type you expecting to meet.

-> Value

The actual value encountered.

-> Converter a 

Produce an error message like converting XXX failed, expected XXX, encountered XXX.

withScientific :: Text -> (Scientific -> Converter a) -> Value -> Converter a Source #

withScientific name f value applies f to the Scientific number when value is a Number and fails using typeMismatch otherwise.

Warning: If you are converting from a scientific to an unbounded type such as Integer you may want to add a restriction on the size of the exponent (see withBoundedScientific) to prevent malicious input from filling up the memory of the target system.

Error message example

withScientific "MyType" f (String "oops")
-- Error: "converting MyType failed, expected Number, but encountered String"

withBoundedScientific :: Text -> (Scientific -> Converter a) -> Value -> Converter a Source #

withBoundedScientific name f value applies f to the Scientific number when value is a Number with exponent less than or equal to 1024.

withRealFloat :: RealFloat a => Text -> (a -> Converter r) -> Value -> Converter r Source #

@withRealFloat try to convert floating number with following rules:

  • Use ±Infinity to represent out of range numbers.
  • Convert Null as NaN

withBoundedIntegral :: (Bounded a, Integral a) => Text -> (a -> Converter r) -> Value -> Converter r Source #

withBoundedScientific name f value applies f to the Scientific number when value is a Number and value is within minBound ~ maxBound.

withKeyValues :: Text -> (Vector (Text, Value) -> Converter a) -> Value -> Converter a Source #

Directly use Object as key-values for further converting.

withFlatMap :: Text -> (FlatMap Text Value -> Converter a) -> Value -> Converter a Source #

Take a Object as an 'FM.FlatMap T.Text Value', on key duplication prefer first one.

withFlatMapR :: Text -> (FlatMap Text Value -> Converter a) -> Value -> Converter a Source #

Take a Object as an 'FM.FlatMap T.Text Value', on key duplication prefer last one.

withHashMap :: Text -> (HashMap Text Value -> Converter a) -> Value -> Converter a Source #

Take a Object as an 'HM.HashMap T.Text Value', on key duplication prefer first one.

withHashMapR :: Text -> (HashMap Text Value -> Converter a) -> Value -> Converter a Source #

Take a Object as an 'HM.HashMap T.Text Value', on key duplication prefer last one.

withEmbeddedJSON Source #

Arguments

:: Text

data type name

-> (Value -> Converter a)

a inner converter which will get the converted Value.

-> Value 
-> Converter a 

Decode a nested JSON-encoded string.

(.:) :: JSON a => FlatMap Text Value -> Text -> Converter a Source #

Retrieve the value associated with the given key of an Object. The result is empty if the key is not present or the value cannot be converted to the desired type.

This accessor is appropriate if the key and value must be present in an object for it to be valid. If the key and value are optional, use .:? instead.

(.:?) :: JSON a => FlatMap Text Value -> Text -> Converter (Maybe a) Source #

Retrieve the value associated with the given key of an Object. The result is Nothing if the key is not present or if its value is Null, or fail if the value cannot be converted to the desired type.

This accessor is most useful if the key and value can be absent from an object without affecting its validity. If the key and value are mandatory, use .: instead.

(.:!) :: JSON a => FlatMap Text Value -> Text -> Converter (Maybe a) Source #

Retrieve the value associated with the given key of an Object. The result is Nothing if the key is not present or fail if the value cannot be converted to the desired type.

This differs from .:? by attempting to convert Null the same as any other JSON value, instead of interpreting it as Nothing.

convertField Source #

Arguments

:: (Value -> Converter a)

the field converter (value part of a key value pair)

-> FlatMap Text Value 
-> Text 
-> Converter a 

convertFieldMaybe :: (Value -> Converter a) -> FlatMap Text Value -> Text -> Converter (Maybe a) Source #

Variant of .:? with explicit converter function.

convertFieldMaybe' :: (Value -> Converter a) -> FlatMap Text Value -> Text -> Converter (Maybe a) Source #

Variant of .:! with explicit converter function.

Helper for manually writing instance.

(.=) :: JSON v => Text -> v -> (Text, Value) infixr 8 Source #

Connect key and value to a tuple to be used with object.

object :: [(Text, Value)] -> Value Source #

Alias for Object . pack.

(.!) :: JSON v => Text -> v -> KVItem infixr 8 Source #

Connect key and value to a KVItem using colon, key will be escaped.

object' :: KVItem -> Builder () Source #

Add curly for comma connected KVItems.

data KVItem Source #

A newtype for Builder, whose semigroup's instance is to connect two builder with comma.

Instances

Instances details
Semigroup KVItem Source # 
Instance details

Defined in Z.Data.JSON.Base