rosa/Json.hs

module Json
( (|.)
, (|:)
, repr
, jprint
) 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) 0

-- Create a String representation of a JSON
repr :: Value -> String
repr obj = drop 1 $ repr' obj 0

-- Create a String representation of a JSON Value
repr' :: Value -> Int -> String
repr' val lev =
  case val of
    Array  x -> intercalate ", " $ mapl (\i -> repr' i lev) x
    Object x -> concat $ map (dump x) $ H.keys x
    String x -> unpack x
    Number x -> show x
    Bool   x -> show x
    Null     -> "null"
  where
    indent   = '\n' : (concat . replicate lev) "  "
    dump o k = concat [indent, unpack k, ": ", repr' (o |. k) (lev+1)]
    mapl f v = V.toList $ V.map f v

-- Print a representation of a JSON Value
jprint :: Value -> IO ()
jprint = putStrLn . repr