Fix compatibility with aeson-1

We still want this because HLS has to build with `aeson-1` on GHC 8.10
due to other libraries.

Author: michaelpj

lsp-types/src/Data/Row/Aeson.hs

@@ -19,7 +19,6 @@ This is crucial to match what LSP clients expect.
 module Data.Row.Aeson where
 
 import           Data.Aeson
-import           Data.Aeson.KeyMap     (singleton)
 import           Data.Aeson.Types      (Parser, typeMismatch)
 import           Data.List             (intercalate)
 
@@ -39,25 +38,27 @@ import           Data.String
 -- | Serialise a value as an entry in a JSON object. This allows customizing the
 -- behaviour in the object context, in order to e.g. omit the field.
 class ToJSONEntry a where
-  toJSONEntry :: Key -> a -> Object
+  -- We use String so we can use fromString on it to get a key that works
+  -- in both aeson-1 and aeson-2
+  toJSONEntry :: String -> a -> Object
 
 instance {-# OVERLAPPING #-} ToJSON a => ToJSONEntry (Maybe a) where
   -- Omit Nothing fields
   toJSONEntry _ Nothing = mempty
-  toJSONEntry k v       = singleton k (toJSON v)
+  toJSONEntry k v       = fromString k .= toJSON v
 
 instance {-# OVERLAPPABLE #-} ToJSON a => ToJSONEntry a where
-  toJSONEntry k v = singleton k (toJSON v)
+  toJSONEntry k v = fromString k .= toJSON v
 
 class FromJSONEntry a where
-  parseJSONEntry :: Object -> Key -> Parser a
+  parseJSONEntry :: Object -> String -> Parser a
 
 instance {-# OVERLAPPING #-} FromJSON a => FromJSONEntry (Maybe a) where
   -- Parse Nothing fields as optional
-  parseJSONEntry o k = o .:? k
+  parseJSONEntry o k = o .:? (fromString k)
 
 instance {-# OVERLAPPABLE #-} FromJSON a => FromJSONEntry a where
-  parseJSONEntry o k = o .: k
+  parseJSONEntry o k = o .: (fromString k)
 
 ------
 

lsp-types/src/Language/LSP/Protocol/Types/Common.hs

@@ -27,6 +27,7 @@ import           Control.Lens
 import           Data.Aeson          hiding (Null)
 import qualified Data.Aeson          as J
 import           Data.Hashable
+import           Data.String         (fromString)
 import           Data.Int            (Int32)
 import           Data.Mod.Word
 import           GHC.Generics        hiding (UInt)
@@ -122,8 +123,10 @@ nullToMaybe :: a |? Null -> Maybe a
 nullToMaybe (InL a) = Just a
 nullToMaybe (InR _) = Nothing
 
+  -- We use String so we can use fromString on it to get a key that works
+  -- in both aeson-1 and aeson-2
 -- | Include a value in an JSON object optionally, omitting it if it is 'Nothing'.
-(.=?) :: (J.KeyValue kv, J.ToJSON v) => J.Key -> Maybe v -> [kv]
+(.=?) :: (J.KeyValue kv, J.ToJSON v) => String -> Maybe v -> [kv]
 k .=? v = case v of
-  Just v' -> [k J..= v']
+  Just v' -> [fromString k J..= v']
   Nothing -> mempty