deriving FromJSON and ToJSON for Literal

main.hs

{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE ExplicitForAll #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE DeriveAnyClass #-}

import Data.Aeson
import Data.Text
import Control.Applicative
import Control.Monad
import qualified Data.ByteString.Lazy as B
import Network.HTTP.Conduit (simpleHttp)
import GHC.Generics

import System.Environment
import Language.Haskell.Exts
import Language.Haskell.Exts.Pretty

deriving instance Generic Literal l
deriving instance ToJSON Literal l
deriving instance FromJSON Literal l

deriving instance Generic SrcSpanInfo
deriving instance ToJSON SrcSpanInfo
deriving instance FromJSON SrcSpanInfo

deriving instance Generic SrcSpan
deriving instance ToJSON SrcSpan
deriving instance FromJSON SrcSpan

main = do
 let ind l n = if Prelude.length l > n then Just $ l !! n else Nothing
 args <- getArgs
 let file = ind args 0
 let inp = maybe getContents readFile file
 fileContents <- inp
 putStrLn fileContents
 let ast = fromParseResult $ parseFileContents fileContents
 putStrLn "ast:"
 putStrLn $ show $ ast
 let original = SrcSpanInfo {srcInfoSpan = SrcSpan "<unknown>.hs" 1 1 4 1, srcInfoPoints = [SrcSpan "<unknown>.hs" 1 1 1 1,SrcSpan "<unknown>.hs" 2 1 2 1,SrcSpan "<unknown>.hs" 2 1 2 1,SrcSpan "<unknown>.hs" 2 1 2 1,SrcSpan "<unknown>.hs" 4 1 4 1,SrcSpan "<unknown>.hs" 4 1 4 1]}
 --let original = SrcSpan "<unknown>.hs" 1 1 4 1
 putStrLn "original:"
 putStrLn $ show original
 let encoded = encode original
 putStrLn "encoded:"
 print encoded
 let eitherDecodedOrString = eitherDecode encoded :: Either String SrcSpanInfo
 case eitherDecodedOrString of
  Left s -> putStrLn s
  Right decoded -> do
   putStrLn "decoded:"
   putStrLn $ show decoded
   putStrLn $ show $ decoded == original