43ea36d · typeable/aeson

git.iko.soy/typeable/aeson

Merge pull request #69 from basvandijk/eitherDecode

Added eitherDecode and eitherDecode'

commit43ea36d090c2bd13ab97297e48011737e95aaa3e authorBryan O'Sullivan <bos@serpentine.com> dateMon 19 Nov 2012, 20:34 (14 years ago) parente3babd5 83078ea

2 files changed+23−1

compare with master

unifiedsplit

Data/Aeson.hs+13−1 Data/Aeson/Parser/Internal.hs+10

Data/Aeson.hs+13−1

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

1616 -- * Encoding and decoding

1717 decode

1818 , decode'

19+ , eitherDecode

20+ , eitherDecode'

1921 , encode

2022 -- * Core JSON types

2123 , Value(..)

@@ -46,7 +48,7 @@ module Data.Aeson

4648 ) where

4749

4850import Data.Aeson.Encode (encode)

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

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

5052import Data.Aeson.Types

5153import qualified Data.ByteString.Lazy as L

5254

@@ -69,3 +71,13 @@ decode = decodeWith json fromJSON

6971decode' :: (FromJSON a) => L.ByteString -> Maybe a

7072decode' = decodeWith json' fromJSON

7173{-# INLINE decode' #-}

74+

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

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

77+eitherDecode = eitherDecodeWith json fromJSON

78+{-# INLINE eitherDecode #-}

79+

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

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

82+eitherDecode' = eitherDecodeWith json' fromJSON

83+{-# INLINE eitherDecode' #-}

Data/Aeson/Parser/Internal.hs+10

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

2323 , value'

2424 -- * Helpers

2525 , decodeWith

26+ , eitherDecodeWith

2627 ) where

2728

2829import Blaze.ByteString.Builder (fromByteString, toByteString)

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

238239 _ -> Nothing

239240{-# INLINE decodeWith #-}

240241

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+

241251-- $lazy

242252--

243253-- The 'json' and 'value' parsers decouple identification from