83078ea · typeable/aeson

git.iko.soy/typeable/aeson

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Added eitherDecode and eitherDecode'

83078eaBas van Dijk15 years ago

Data/Aeson.hs+13−1

compare with master

unifiedsplit

@@ -16,6 +16,8 @@ module Data.Aeson

16 -- * Encoding and decoding

17 decode

18 , decode'

19+ , eitherDecode

20+ , eitherDecode'

19 , encode

21 , encode

20 -- * Core JSON types

22 -- * Core JSON types

21 , Value(..)

23 , Value(..)

@@ -40,7 +42,7 @@ module Data.Aeson

40 ) where

42 ) where

42import Data.Aeson.Encode (encode)

44import Data.Aeson.Encode (encode)

43−import Data.Aeson.Parser.Internal (decodeWith, json, json')

45+import Data.Aeson.Parser.Internal (decodeWith, eitherDecodeWith, json, json')

44import Data.Aeson.Types

46import Data.Aeson.Types

45import qualified Data.ByteString.Lazy as L

47import qualified Data.ByteString.Lazy as L

@@ -63,3 +65,13 @@ decode = decodeWith json fromJSON

63decode' :: (FromJSON a) => L.ByteString -> Maybe a

65decode' :: (FromJSON a) => L.ByteString -> Maybe a

64decode' = decodeWith json' fromJSON

66decode' = decodeWith json' fromJSON

65{-# INLINE decode' #-}

67{-# INLINE decode' #-}

68+

69+-- | Like 'decode' but returns an error message when decoding fails.

70+eitherDecode :: (FromJSON a) => L.ByteString -> Either String a

71+eitherDecode = eitherDecodeWith json fromJSON

72+{-# INLINE eitherDecode #-}

73+

74+-- | Like 'decode'' but returns an error message when decoding fails.

75+eitherDecode' :: (FromJSON a) => L.ByteString -> Either String a

76+eitherDecode' = eitherDecodeWith json' fromJSON

77+{-# INLINE eitherDecode' #-}

Data/Aeson/Parser/Internal.hs+10

@@ -23,6 +23,7 @@ module Data.Aeson.Parser.Internal

23 , value'

24 -- * Helpers

25 , decodeWith

26+ , eitherDecodeWith

26 ) where

27 ) where

28import Blaze.ByteString.Builder (fromByteString, toByteString)

29import Blaze.ByteString.Builder (fromByteString, toByteString)

@@ -238,6 +239,15 @@ decodeWith p to s =

238 _ -> Nothing

239 _ -> Nothing

239{-# INLINE decodeWith #-}

240{-# INLINE decodeWith #-}

240

241

242+eitherDecodeWith :: Parser Value -> (Value -> Result a) -> L.ByteString -> Either String a

243+eitherDecodeWith p to s =

244+ case L.parse p s of

245+ L.Done _ v -> case to v of

246+ Success a -> Right a

247+ Error msg -> Left msg

248+ L.Fail _ _ msg -> Left msg

249+{-# INLINE eitherDecodeWith #-}

250+

241-- $lazy

251-- $lazy

242--

252--

243-- The 'json' and 'value' parsers decouple identification from

253-- The 'json' and 'value' parsers decouple identification from