Failed to parse field some-string: expected Text, encountered Null

[tolysz]

I am testing the git.master version and got this error:

Object (fromList [("some-string",Null)])
aeson-example-simple: failed to parse field some-string: expected Text, encountered Null

I would expect that fromJSON would coerce Null to Nothing :: Maybe Text but it sees Null as a Type ( I tested it on both GHC 7.10.2 and 7.10.3 )

Which is a result of the following code:

{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE OverloadedStrings #-}

import Data.Aeson
import Data.Text

data Some = Some {someString :: Maybe Text}
  deriving Show

instance FromJSON Some where
  parseJSON = withObject "Some" $ \o -> do
        someString     <- o .:?  "some-string"
        return Some{..}

a :: Value
a = object ([("some-string",Null)])

main = do
   print a
   case fromJSON $ a of
       Error e -> error e
       Success some -> print (some :: Some)

and in .cabal

executable aeson-example-simple
  main-is: Simple.hs
  ghc-options: -Wall
  build-depends:
    aeson,
    base,
    bytestring,
    text

I will investigate it a bit longer but if you have anything to suggest It would be awesome...

[bergmark]

This seems to have been fixed. Currently on master:

λ> main
Object (fromList [("some-string",Null)])
Some {someString = Nothing}