typeerrors.hs

import Data.IntMap (IntMap)
import qualified Data.IntMap as IM
import qualified Data.HashMap.Strict as HM
import Data.Aeson

transformIM :: ToJSON a => IntMap a -> Object
transformIM = HM.map toJSON . HM.fromList . convertKeys . IM.toList
    where convertKeys = map (\(k, v) -> (T.pack $ show k, v))

    Couldn't match type `HM.HashMap Text Value'
                  with `unordered-containers-0.2.3.1:Data.HashMap.Base.HashMap
                          Text Value'
    Expected type: HM.HashMap Text a -> Object
      Actual type: HM.HashMap Text a -> HM.HashMap Text Value
    In the return type of a call of `HM.map'
    In the first argument of `(.)', namely `HM.map toJSON'
    In the expression:
      HM.map toJSON . HM.fromList . convertKeys . IM.toList