Experiment with Free-Church encoding in DBTx

src/Gargantext/Database/Transactional.hs

@@ -42,6 +42,7 @@ import Database.PostgreSQL.Simple.Transaction qualified as PG
 import Gargantext.Database.Class
 import Opaleye
 import Prelude
+import Control.Monad.Free.Church
 
 data DBOperation = DBRead | DBWrite
 
@@ -75,7 +76,7 @@ data DBTransactionOp err (r :: DBOperation) next where
   -- | Monadic failure for DB transactions.
   DBFail    :: err -> DBTransactionOp err r next
 
-newtype DBTx err r a = DBTx { _DBTx :: Free (DBTransactionOp err r) a }
+newtype DBTx err r a = DBTx { _DBTx :: F (DBTransactionOp err r) a }
   deriving (Functor, Applicative, Monad)
 
 type DBQuery err r a    = DBTx err r a
@@ -130,7 +131,7 @@ withReadOnlyTransactionM conn action =
 runDBTx :: DBUpdate err a -> DBTxCmd err a
 runDBTx (DBTx m) = do
   pool <- view connPool
-  withResourceM pool $ \conn -> withTransactionM conn $ foldFree (evalOp conn) m
+  withResourceM pool $ \conn -> withTransactionM conn $ foldF (evalOp conn) m
 
 -- | /NOTE/ the input type is 'DBReadOnly', i.e. a transaction where /all/
 -- the operations are 'DBRead'. This makes impossible to sneak in updates
@@ -138,7 +139,7 @@ runDBTx (DBTx m) = do
 runDBQuery :: DBReadOnly err r a -> DBTxCmd err a
 runDBQuery (DBTx m) = do
   pool <- view connPool
-  withResourceM pool $ \conn -> withReadOnlyTransactionM conn $ foldFree (evalOp conn) m
+  withResourceM pool $ \conn -> withReadOnlyTransactionM conn $ foldF (evalOp conn) m
 
 -- | The main evaluator, turns our pure operations into side-effects that run into the
 -- 'DBCmd'.