rosa/Json.hs
2014-12-27 16:34:29 +01:00

38 lines
1.1 KiB
Haskell

module Json where
import Data.Aeson
import Data.Aeson.Types (parse)
import Data.Text (Text, unpack)
import Data.List (intercalate)
import qualified Data.Vector as V
import qualified Data.HashMap.Strict as H
-- Get the JSON value of a key
(|.) :: Object -> Text -> Value
obj |. key = case parse (.: key) obj of
Success val -> val
Error err -> toJSON err
-- Get the String value of a key
(|:) :: Object -> Text -> String
obj |: key = repr (obj |. key)
-- Create a String representation of a JSON value
repr :: Value -> String
repr obj = repr' obj 0 where
repr' val lev =
case val of
Array x -> intercalate ", " $ mapl (\i -> repr' i lev) x
Object x -> drop 1 $ concat $ map (dump x lev) $ H.keys x
String x -> unpack x
Number x -> show x
Bool x -> show x
Null -> "null"
mapl f v = V.toList $ V.map f v
indent l = '\n' : (concat . replicate l) " "
dump o l k = concat [indent l, unpack k, ": ", repr' (o |. k) (l+1)]
-- Pretty print a JSON value
pprint :: Value -> IO ()
pprint = putStrLn . repr