Replace mapLeft with first

library/Hasql/Decoders/Result.hs

@@ -51,7 +51,7 @@ rowsAffected =
             then Left (UnexpectedResultError "Empty bytes")
             else Right bytes
         decimal bytes =
-          mapLeft (\m -> UnexpectedResultError ("Decimal parsing failure: " <> fromString m))
+          first (\m -> UnexpectedResultError ("Decimal parsing failure: " <> fromString m))
             $ Attoparsec.parseOnly (Attoparsec.decimal <* Attoparsec.endOfInput) bytes
 
 {-# INLINE checkExecStatus #-}
@@ -112,7 +112,7 @@ maybe rowDec =
           0 -> return (Right Nothing)
           1 -> do
             maxCols <- LibPQ.nfields result
-            fmap (fmap Just . mapLeft (RowResultError 0)) $ Row.run rowDec (result, 0, maxCols, integerDatetimes)
+            fmap (fmap Just . first (RowResultError 0)) $ Row.run rowDec (result, 0, maxCols, integerDatetimes)
           _ -> return (Left (UnexpectedAmountOfRowsResultError (rowToInt maxRows)))
   where
     rowToInt (LibPQ.Row n) =
@@ -130,7 +130,7 @@ single rowDec =
         case maxRows of
           1 -> do
             maxCols <- LibPQ.nfields result
-            fmap (mapLeft (RowResultError 0)) $ Row.run rowDec (result, 0, maxCols, integerDatetimes)
+            fmap (first (RowResultError 0)) $ Row.run rowDec (result, 0, maxCols, integerDatetimes)
           _ -> return (Left (UnexpectedAmountOfRowsResultError (rowToInt maxRows)))
   where
     rowToInt (LibPQ.Row n) =

library/Hasql/Decoders/Results.hs

@@ -45,7 +45,7 @@ single resultDec =
       resultMaybe <- LibPQ.getResult connection
       case resultMaybe of
         Just result ->
-          mapLeft ResultCommandError <$> Result.run resultDec integerDatetimes result
+          first ResultCommandError <$> Result.run resultDec integerDatetimes result
         Nothing ->
           fmap (Left . ClientCommandError) (LibPQ.errorMessage connection)
 
@@ -64,11 +64,11 @@ dropRemainders =
           loop integerDatetimes connection <* checkErrors
           where
             checkErrors =
-              ExceptT $ fmap (mapLeft ResultCommandError) $ Result.run Result.noResult integerDatetimes result
+              ExceptT $ fmap (first ResultCommandError) $ Result.run Result.noResult integerDatetimes result
 
 refine :: (a -> Either Text b) -> Results a -> Results b
 refine refiner (Results stack) = Results
   $ ReaderT
   $ \env -> ExceptT $ do
     resultEither <- runExceptT $ runReaderT stack env
-    return $ resultEither >>= mapLeft (ResultCommandError . UnexpectedResultError) . refiner
+    return $ resultEither >>= first (ResultCommandError . UnexpectedResultError) . refiner

library/Hasql/Decoders/Row.hs

@@ -55,7 +55,7 @@ value valueDec =
                 Right Nothing
               Just value ->
                 fmap Just
-                  $ mapLeft ValueColumnError
+                  $ first ValueColumnError
                   $ {-# SCC "decode" #-} A.valueParser (Value.run valueDec integerDatetimes) value
         else pure (Left EndOfInputColumnError)
 

library/Hasql/Pipeline/Core.hs

@@ -45,7 +45,7 @@ run (Pipeline sendQueriesInIO) connection registry integerDatetimes = do
     runResultsDecoder :: forall a. Decoders.Results.Results a -> ExceptT SessionError IO a
     runResultsDecoder decoder =
       ExceptT
-        $ fmap (mapLeft PipelineSessionError)
+        $ fmap (first PipelineSessionError)
         $ Decoders.Results.run decoder connection integerDatetimes
 
     runCommand :: IO Bool -> ExceptT SessionError IO ()
@@ -109,7 +109,7 @@ statement params (Statement.Statement sql (Encoders.Params encoder) (Decoders.Re
                       else (False,) . Left . commandToSessionError . ClientCommandError <$> Pq.errorMessage connection
                   where
                     recv =
-                      fmap (mapLeft commandToSessionError)
+                      fmap (first commandToSessionError)
                         $ (<*)
                         <$> Decoders.Results.run (Decoders.Results.single Decoders.Result.noResult) connection integerDatetimes
                         <*> Decoders.Results.run Decoders.Results.dropRemainders connection integerDatetimes
@@ -122,7 +122,7 @@ statement params (Statement.Statement sql (Encoders.Params encoder) (Decoders.Re
                 True -> pure (Right recv)
               where
                 recv =
-                  fmap (mapLeft commandToSessionError)
+                  fmap (first commandToSessionError)
                     $ (<*)
                     <$> Decoders.Results.run decoder connection integerDatetimes
                     <*> Decoders.Results.run Decoders.Results.dropRemainders connection integerDatetimes
@@ -133,7 +133,7 @@ statement params (Statement.Statement sql (Encoders.Params encoder) (Decoders.Re
             True -> pure (Right recv)
           where
             recv =
-              fmap (mapLeft commandToSessionError)
+              fmap (first commandToSessionError)
                 $ (<*)
                 <$> Decoders.Results.run decoder connection integerDatetimes
                 <*> Decoders.Results.run Decoders.Results.dropRemainders connection integerDatetimes

library/Hasql/Prelude.hs

@@ -7,7 +7,6 @@ module Hasql.Prelude
     forMToZero_,
     forMFromZero_,
     strictCons,
-    mapLeft,
   )
 where
 
@@ -130,8 +129,3 @@ forMFromZero_ !endN f =
 strictCons :: a -> [a] -> [a]
 strictCons !a b =
   let !c = a : b in c
-
-{-# INLINE mapLeft #-}
-mapLeft :: (a -> c) -> Either a b -> Either c b
-mapLeft f =
-  either (Left . f) Right

library/Hasql/Session/Core.hs

@@ -35,7 +35,7 @@ sql sql =
     $ ReaderT
     $ \(Connection.Connection pqConnectionRef integerDatetimes registry) ->
       ExceptT
-        $ fmap (mapLeft (QuerySessionError sql []))
+        $ fmap (first (QuerySessionError sql []))
         $ withMVar pqConnectionRef
         $ \pqConnection -> do
           r1 <- IO.sendNonparametricStatement pqConnection sql
@@ -53,7 +53,7 @@ statement input (Statement.Statement template (Encoders.Params paramsEncoder) (D
     $ ReaderT
     $ \(Connection.Connection pqConnectionRef integerDatetimes registry) ->
       ExceptT
-        $ fmap (mapLeft (QuerySessionError template (Encoders.Params.renderReadable paramsEncoder input)))
+        $ fmap (first (QuerySessionError template (Encoders.Params.renderReadable paramsEncoder input)))
         $ withMVar pqConnectionRef
         $ \pqConnection -> do
           r1 <- IO.sendParametricStatement pqConnection integerDatetimes registry template paramsEncoder preparable input

testing-kit/Hasql/TestingKit/TestingDsl.hs

@@ -37,10 +37,10 @@ runSessionOnLocalDb session =
   runExceptT $ acquire >>= \connection -> use connection <* release connection
   where
     acquire =
-      ExceptT $ fmap (mapLeft ConnectionError) $ Connection.acquire Constants.localConnectionSettings
+      ExceptT $ fmap (first ConnectionError) $ Connection.acquire Constants.localConnectionSettings
     use connection =
       ExceptT
-        $ fmap (mapLeft SessionError)
+        $ fmap (first SessionError)
         $ Session.run session connection
     release connection =
       lift $ Connection.release connection