d2e9655 · typeable/aeson

git.iko.soy/typeable/aeson

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add new accessor (.:/) to allow default value

d2e9655Luis Cabellos15 years ago

Data/Aeson.hs+1

compare with master

unifiedsplit

@@ -30,6 +30,7 @@ module Data.Aeson

30 , (.=)

31 , (.:)

32 , (.:?)

33+ , (.:/)

33 , object

34 , object

34 -- * Parsing

35 -- * Parsing

35 , json

36 , json

Data/Aeson/Types.hs+1

@@ -35,6 +35,7 @@ module Data.Aeson.Types

35 , (.=)

36 , (.:)

37 , (.:?)

38+ , (.:/)

38 , object

39 , object

39 ) where

40 ) where

Data/Aeson/Types/Class.hs+15

@@ -33,6 +33,7 @@ module Data.Aeson.Types.Class

33 , fromJSON

34 , (.:)

35 , (.:?)

36+ , (.:/)

36 , (.=)

37 , (.=)

37 , typeMismatch

38 , typeMismatch

38 ) where

39 ) where

@@ -707,6 +708,20 @@ obj .:? key = case M.lookup key obj of

707 Just v -> parseJSON v

708 Just v -> parseJSON v

708{-# INLINE (.:?) #-}

709{-# INLINE (.:?) #-}

709

710

711+-- | Retrieve the value associated with the given key of an 'Object'.

712+-- The result is a default value if the key is not present, or 'empty'

713+-- if the value cannot be converted to the desired type.

714+--

715+-- This accessor is most useful if the key and value can be absent

716+-- from an object without affecting its validity and we know a

717+-- default value to assign in that case. If the key and value

718+-- are mandatory, use '(.:)' instead.

719+(.:/) :: (FromJSON a) => Object -> (Text, a) -> Parser a

720+obj .:/ (key, val) = case M.lookup key obj of

721+ Nothing -> pure val

722+ Just v -> parseJSON v

723+{-# INLINE (.:/) #-}

724+

710

725

711-- | Fail parsing due to a type mismatch, with a descriptive message.

726-- | Fail parsing due to a type mismatch, with a descriptive message.

712typeMismatch :: String -- ^ The name of the type you are trying to parse.

727typeMismatch :: String -- ^ The name of the type you are trying to parse.