Core.Encoding.Json

Encoding and decoding UTF-8 JSON content.

This module is a thin wrapper around the most excellent aeson library, which has rich and powerful facilities for encoding Haskell types into JSON.

Quite often, however, you find yourself having to create a Haskell type just to read some JSON coming from an external web service or API. This can be challenging when the source of the JSON is complex or varying its schema over time. For ease of exploration this module simply defines an easy to use intermediate type representing JSON as a format.

Often you'll be working with literals directly in your code. While you can write:

    j = JsonObject (intoMap [(JsonKey "answer", JsonNumber 42)])

and it would be correct, enabling:

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE OverloadedLists #-}

allows you to write:

    j = JsonObject [("answer", 42)]

which you is somewhat less cumbersome in declaration-heavy code. You're certainly welcome to use the constructors if you find it makes for more readable code or if you need the type annotations.

Encoding and Decoding

encodeToUTF8 :: JsonValue -> Bytes

Given a JSON value, encode it to UTF-8 bytes

I know we're not supposed to rely on types to document functions, but really, this one does what it says on the tin.

encodeToRope :: JsonValue -> Rope

Given a JSON value, encode it to a Rope (which, by definition, is UTF-8 internally).

decodeFromUTF8 :: Bytes -> Maybe JsonValue

Given an array of bytes, attempt to decode it as a JSON value.

decodeFromRope :: Rope -> Maybe JsonValue

Given an string that is full of a bunch of JSON, attempt to decode it.

data JsonValue

A JSON value.

Constructors

JsonObject (Map JsonKey JsonValue)

JsonArray [JsonValue]

JsonString Rope

JsonNumber Scientific

JsonBool Bool

JsonNull

Instances

IsString JsonValue

Defined in Core.Encoding.Json

Methods

fromString :: String -> JsonValue

Generic JsonValue

Defined in Core.Encoding.Json

Associated Types

type Rep JsonValue :: Type -> Type

Methods

from :: JsonValue -> Rep JsonValue x

to :: Rep JsonValue x -> JsonValue

Num JsonValue

Defined in Core.Encoding.Json

Methods

(+) :: JsonValue -> JsonValue -> JsonValue

(-) :: JsonValue -> JsonValue -> JsonValue

(*) :: JsonValue -> JsonValue -> JsonValue

negate :: JsonValue -> JsonValue

abs :: JsonValue -> JsonValue

signum :: JsonValue -> JsonValue

fromInteger :: Integer -> JsonValue

Fractional JsonValue

Defined in Core.Encoding.Json

Methods

(/) :: JsonValue -> JsonValue -> JsonValue

recip :: JsonValue -> JsonValue

fromRational :: Rational -> JsonValue

Show JsonValue

Defined in Core.Encoding.Json

Methods

showsPrec :: Int -> JsonValue -> ShowS

show :: JsonValue -> String

showList :: [JsonValue] -> ShowS

Render JsonValue

Defined in Core.Encoding.Json

Associated Types

type Token JsonValue

Methods

colourize :: Token JsonValue -> AnsiColour

highlight :: JsonValue -> Doc (Token JsonValue)

Eq JsonValue

Defined in Core.Encoding.Json

Methods

(==) :: JsonValue -> JsonValue -> Bool

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

Pretty JsonValue

Defined in Core.Encoding.Json

Methods

pretty :: JsonValue -> Doc ann

prettyList :: [JsonValue] -> Doc ann

type Rep JsonValue

Defined in Core.Encoding.Json

type Rep JsonValue = D1 ('MetaData "JsonValue" "Core.Encoding.Json" "core-data-0.3.9.1-4CvEmGx8i3c5MFf0Lr0y5T" 'False) ((C1 ('MetaCons "JsonObject" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedStrict) (Rec0 (Map JsonKey JsonValue))) :+: (C1 ('MetaCons "JsonArray" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedStrict) (Rec0 [JsonValue])) :+: C1 ('MetaCons "JsonString" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedStrict) (Rec0 Rope)))) :+: (C1 ('MetaCons "JsonNumber" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedStrict) (Rec0 Scientific)) :+: (C1 ('MetaCons "JsonBool" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedStrict) (Rec0 Bool)) :+: C1 ('MetaCons "JsonNull" 'PrefixI 'False) (U1 :: Type -> Type))))

type Token JsonValue

Defined in Core.Encoding.Json

type Token JsonValue = JsonToken

newtype JsonKey

Keys in a JSON object.

Constructors

JsonKey Rope

Instances

IsString JsonKey

Defined in Core.Encoding.Json

Methods

fromString :: String -> JsonKey

Generic JsonKey

Defined in Core.Encoding.Json

Associated Types

type Rep JsonKey :: Type -> Type

Methods

from :: JsonKey -> Rep JsonKey x

to :: Rep JsonKey x -> JsonKey

Show JsonKey

Defined in Core.Encoding.Json

Methods

showsPrec :: Int -> JsonKey -> ShowS

show :: JsonKey -> String

showList :: [JsonKey] -> ShowS

Key JsonKey

Defined in Core.Encoding.Json

Textual JsonKey

Defined in Core.Encoding.Json

Methods

fromRope :: Rope -> JsonKey

intoRope :: JsonKey -> Rope

appendRope :: JsonKey -> Rope -> Rope

Render JsonKey

Defined in Core.Encoding.Json

Associated Types

type Token JsonKey

Methods

colourize :: Token JsonKey -> AnsiColour

highlight :: JsonKey -> Doc (Token JsonKey)

Eq JsonKey

Defined in Core.Encoding.Json

Methods

(==) :: JsonKey -> JsonKey -> Bool

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

Ord JsonKey

Defined in Core.Encoding.Json

Methods

compare :: JsonKey -> JsonKey -> Ordering

(<) :: JsonKey -> JsonKey -> Bool

(<=) :: JsonKey -> JsonKey -> Bool

(>) :: JsonKey -> JsonKey -> Bool

(>=) :: JsonKey -> JsonKey -> Bool

max :: JsonKey -> JsonKey -> JsonKey

min :: JsonKey -> JsonKey -> JsonKey

Hashable JsonKey

Defined in Core.Encoding.Json

Methods

hashWithSalt :: Int -> JsonKey -> Int

hash :: JsonKey -> Int

Pretty JsonKey

Defined in Core.Encoding.Json

Methods

pretty :: JsonKey -> Doc ann

prettyList :: [JsonKey] -> Doc ann

type Rep JsonKey

Defined in Core.Encoding.Json

type Rep JsonKey = D1 ('MetaData "JsonKey" "Core.Encoding.Json" "core-data-0.3.9.1-4CvEmGx8i3c5MFf0Lr0y5T" 'True) (C1 ('MetaCons "JsonKey" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Rope)))

type Token JsonKey

Defined in Core.Encoding.Json

type Token JsonKey = JsonToken

Syntax highlighting

data JsonToken

Support for pretty-printing JSON values with syntax highlighting using the prettyprinter library. To output a JSON structure to terminal colourized with ANSI escape codes you can use the Render instance:

    debug "j" (render j)

will get you:

23:46:04Z (00.007) j =
{
    "answer": 42
}

Constructors

SymbolToken

QuoteToken

KeyToken

StringToken

EscapeToken

NumberToken

BooleanToken

LiteralToken

colourizeJson :: JsonToken -> AnsiColour

Used by the Render instance to turn symbolic annotations into ANSI colours annotations. If you're curious, the render pipeline looks like:

    render = intoText . renderStrict . reAnnotateS colourize
                . layoutPretty defaultLayoutOptions . prettyValue

prettyKey :: JsonKey -> Doc JsonToken

prettyValue :: JsonValue -> Doc JsonToken

Orphan instances

FromJSON Rope

Methods

parseJSON :: Value -> Parser Rope

parseJSONList :: Value -> Parser [Rope]