allow using Aeson for streaming JSON output

Keeping Text.JSON use for now, because it seems a better fit for most of
the commands, which don't use very structured JSON objects, but just output
whatever fields suites them. But this lets Aeson be used when a more
structured data type is available to serialize to JSON.

Command/Add.hs

@@ -146,7 +146,7 @@ perform file = do
 
 cleanup :: Key -> Bool -> CommandCleanup
 cleanup key hascontent = do
-	maybeShowJSON [("key", key2file key)]
+	maybeShowJSON $ JSONObject [("key", key2file key)]
 	when hascontent $
 		logStatus key InfoPresent
 	return True

Command/AddUrl.hs

@@ -356,7 +356,7 @@ cleanup u url file key mtmp = case mtmp of
 			)
   where
 	go = do
-		maybeShowJSON [("key", key2file key)]
+		maybeShowJSON $ JSONObject [("key", key2file key)]
 		when (isJust mtmp) $
 			logStatus key InfoPresent
 		setUrlPresent u key url

Command/Find.hs

@@ -66,7 +66,7 @@ start o file key = ifM (limited <||> inAnnex key)
 
 showFormatted :: Maybe Utility.Format.Format -> String -> [(String, String)] -> Annex ()
 showFormatted format unformatted vars =
-	unlessM (showFullJSON vars) $
+	unlessM (showFullJSON $ JSONObject vars) $
 		case format of
 			Nothing -> liftIO $ putStrLn unformatted
 			Just formatter -> liftIO $ putStr $

Command/Info.hs

@@ -250,7 +250,7 @@ nostat = return Nothing
 json :: JSON j => (j -> String) -> StatState j -> String -> StatState String
 json fmt a desc = do
 	j <- a
-	lift $ maybeShowJSON [(desc, j)]
+	lift $ maybeShowJSON $ JSONObject [(desc, j)]
 	return $ fmt j
 
 nojson :: StatState String -> String -> StatState String
@@ -374,7 +374,7 @@ transfer_list :: Stat
 transfer_list = stat desc $ nojson $ lift $ do
 	uuidmap <- Remote.remoteMap id
 	ts <- getTransfers
-	maybeShowJSON [(desc, map (uncurry jsonify) ts)]
+	maybeShowJSON $ JSONObject [(desc, map (uncurry jsonify) ts)]
 	return $ if null ts
 		then "none"
 		else multiLine $

Command/MetaData.hs

@@ -96,7 +96,7 @@ perform now o k = case getSet o of
 cleanup :: Key -> CommandCleanup
 cleanup k = do
 	l <- map unwrapmeta . fromMetaData <$> getCurrentMetaData k
-	maybeShowJSON l
+	maybeShowJSON (JSONObject l)
 	showLongNote $ unlines $ concatMap showmeta l
 	return True
   where

Command/Status.hs

@@ -43,7 +43,7 @@ displayStatus s  = do
 	let c = statusChar s
 	absf <- fromRepo $ fromTopFilePath (statusFile s)
 	f <- liftIO $ relPathCwdToFile absf
-	unlessM (showFullJSON [("status", [c]), ("file", f)]) $
+	unlessM (showFullJSON $ JSONObject [("status", [c]), ("file", f)]) $
 		liftIO $ putStrLn $ [c] ++ " " ++ f
 
 -- Git thinks that present direct mode files are typechanged.