Prove that ReadTSV / WriteTSV classes bubble up through MonadTrans instances

lib/GEODE/Metadata/TSV.hs

@@ -7,6 +7,7 @@ module GEODE.Metadata.TSV
   , fromTSV
   , toTSV ) where
 
+import Control.Monad.Trans (MonadTrans(..))
 import Control.Monad.Except (ExceptT(..))
 import Data.ByteString.Lazy as ByteString
   ( ByteString, getContents, putStr, readFile, writeFile )
@@ -95,6 +96,9 @@ instance FromNamedRecord a => ReadTSV () IO (Document a) where
 instance FromNamedRecord a => ReadTSV FilePath IO (Document a) where
   readTSV path = named <$> ByteString.readFile path >>= try
 
+instance (Monad m, MonadTrans t, ReadTSV s m a) => ReadTSV s (t m) a where
+  readTSV = lift . readTSV
+
 -- * Writing TSV data
 --
 -- | A class type to represent processes which output TSV
@@ -128,3 +132,6 @@ instance ToNamedRecord a => WriteTSV () IO (Document a) where
 instance ToNamedRecord a => WriteTSV FilePath IO (Document a) where
   writeTSV path (Document {header, rows}) =
     ByteString.writeFile path . encodeByNameWith toTSV header $ toList rows
+
+instance (Monad m, MonadTrans t, WriteTSV d m a) => WriteTSV d (t m) a where
+  writeTSV d = lift . writeTSV d