Text.JSON.FromJSValue

Interface for extracting data from JSValue.

Basic Parsing

class FromJSValue a where

Structures that can be parsed from JSON. Instances must declare either fromJSValue (parse directly from JSValue) or fromJSValueM (uses MonadReader)

Methods

fromJSValue :: JSValue -> Maybe a

fromJSValueM :: (JSValueContainer c, MonadReader c m) => m (Maybe a)

Instances

FromJSValue Bool

FromJSValue Int

FromJSValue Integer

FromJSValue String

FromJSValue ByteString

FromJSValue JSValue

FromJSValue a => FromJSValue [a]

FromJSValue a => FromJSValue (Maybe a)

(FromJSValue a, FromJSValue b) => FromJSValue (a, b)

Data Extraction

fromJSValueField :: (JSValueContainer c, MonadReader c m, FromJSValue a) => String -> m (Maybe a)

Reading the value that is on some field. With field if current JSON is not object

fromJSValueFieldBase64 :: (JSValueContainer c, MonadReader c m) => String -> m (Maybe ByteString)

Version of fromJSValueField for Base64 encoded data to avoid memory leak.

fromJSValueFieldCustom :: (JSValueContainer c, MonadReader c m) => String -> m (Maybe a) -> m (Maybe a)

Generalization of fromJSValueField. Does not use FromJSValue instances

fromJSValueCustomMany :: (JSValueContainer c, MonadReader c m) => m (Maybe a) -> m (Maybe [a])

Runs parser on each element of underlaying json. Returns Just iff JSON is array.

fromJSValueCustomList :: (JSValueContainer c, MonadReader c m) => [m (Maybe a)] -> m (Maybe [a])

Generalization of fromJSValueCustomMany, where each element of array can have different parser.

Running

withJSValue :: Monad m => JSValue -> ReaderT JSValue m a -> m a

Simple runner