Change the order of arguments in Unfold.fold

To keep it consistent with Stream.fold.

benchmark/Streamly/Benchmark/Data/Unfold.hs

@@ -62,7 +62,7 @@ source n = UF.enumerateFromToIntegral n
 
 {-# INLINE drainGeneration #-}
 drainGeneration :: Monad m => Unfold m a b -> a -> m ()
-drainGeneration unf seed = UF.fold unf FL.drain seed
+drainGeneration unf seed = UF.fold FL.drain unf seed
 
 {-# INLINE drainTransformation #-}
 drainTransformation ::
@@ -409,7 +409,7 @@ toNullAp value start =
     let end = start + nthRoot 2 value
         s = source end
     -- in UF.fold ((+) <$> s <*> s) FL.drain start
-    in UF.fold ((+) `fmap` s `UF.apply` s) FL.drain start
+    in UF.fold FL.drain ((+) `fmap` s `UF.apply` s) start
 
 {-# INLINE _apDiscardFst #-}
 _apDiscardFst :: Int -> Int -> m ()
@@ -451,7 +451,7 @@ toNull value start =
         u = src `UF.bind` \x ->
             src `UF.bind` \y ->
                 UF.yield (x + y)
-     in UF.fold u FL.drain start
+     in UF.fold FL.drain u start
 
 
 {-# INLINE toNull3 #-}
@@ -469,7 +469,7 @@ toNull3 value start =
         u = src `UF.bind` \x ->
             src `UF.bind` \y ->
                 UF.yield (x + y)
-     in UF.fold u FL.drain start
+     in UF.fold FL.drain u start
 
 {-# INLINE toList #-}
 toList :: Monad m => Int -> Int -> m [Int]
@@ -485,7 +485,7 @@ toList value start = do
         u = src `UF.bind` \x ->
             src `UF.bind` \y ->
                 UF.yield (x + y)
-     in UF.fold u FL.toList start
+     in UF.fold FL.toList u start
 
 {-# INLINE toListSome #-}
 toListSome :: Monad m => Int -> Int -> m [Int]
@@ -501,7 +501,7 @@ toListSome value start = do
         u = src `UF.bind` \x ->
             src `UF.bind` \y ->
                 UF.yield (x + y)
-     in UF.fold (UF.take 1000 u) FL.toList start
+     in UF.fold FL.toList (UF.take 1000 u) start
 
 {-# INLINE filterAllOut #-}
 filterAllOut :: Monad m => Int -> Int -> m ()
@@ -519,7 +519,7 @@ filterAllOut value start = do
              in if s < 0
                 then UF.yield s
                 else UF.nilM (return . const ())
-     in UF.fold u FL.drain start
+     in UF.fold FL.drain u start
 
 {-# INLINE filterAllIn #-}
 filterAllIn :: Monad m => Int -> Int -> m ()
@@ -537,7 +537,7 @@ filterAllIn value start = do
              in if s > 0
                 then UF.yield s
                 else UF.nilM (return . const ())
-     in UF.fold u FL.drain start
+     in UF.fold FL.drain u start
 
 {-# INLINE filterSome #-}
 filterSome :: Monad m => Int -> Int -> m ()
@@ -555,7 +555,7 @@ filterSome value start = do
              in if s > 1100000
                 then UF.yield s
                 else UF.nilM (return . const ())
-     in UF.fold u FL.drain start
+     in UF.fold FL.drain u start
 
 {-# INLINE breakAfterSome #-}
 breakAfterSome :: Int -> Int -> IO ()
@@ -574,7 +574,7 @@ breakAfterSome value start =
                 then error "break"
                 else UF.yield s
      in do
-        (_ :: Either ErrorCall ()) <- try $ UF.fold u FL.drain start
+        (_ :: Either ErrorCall ()) <- try $ UF.fold FL.drain u start
         return ()
 
 -------------------------------------------------------------------------------
@@ -590,9 +590,7 @@ concatCount linearCount =
 concat :: Monad m => Int -> Int -> m ()
 concat linearCount start = do
     let end = start + concatCount linearCount
-    UF.fold
-        (UF.many (source end) (source end))
-        FL.drain start
+    UF.fold FL.drain (UF.many (source end) (source end)) start
 
 -------------------------------------------------------------------------------
 -- Benchmarks

benchmark/Streamly/Benchmark/FileSystem/Handle/ReadWrite.hs

@@ -132,7 +132,7 @@ inspect $ 'readWithBufferOfFromBytesNull `hasNoType` ''D.FoldMany
 -- | Send the chunk content ('defaultChunkSize') to /dev/null
 -- Implicitly benchmarked via 'readFromBytesNull'
 _readChunks :: Handle -> Handle -> IO ()
-_readChunks inh devNull = IUF.fold unf fld inh
+_readChunks inh devNull = IUF.fold fld unf inh
 
     where
 
@@ -142,7 +142,7 @@ _readChunks inh devNull = IUF.fold unf fld inh
 -- | Send the chunk content to /dev/null
 -- Implicitly benchmarked via 'readWithBufferOfFromBytesNull'
 _readChunksWithBufferOf :: Handle -> Handle -> IO ()
-_readChunksWithBufferOf inh devNull = IUF.fold unf fld (defaultChunkSize, inh)
+_readChunksWithBufferOf inh devNull = IUF.fold fld unf (defaultChunkSize, inh)
 
     where
 
@@ -163,7 +163,7 @@ o_1_space_copy_fromBytes env =
 -- | Send the file contents ('defaultChunkSize') to /dev/null
 {-# NOINLINE writeReadWithBufferOf #-}
 writeReadWithBufferOf :: Handle -> Handle -> IO ()
-writeReadWithBufferOf inh devNull = IUF.fold unf fld (defaultChunkSize, inh)
+writeReadWithBufferOf inh devNull = IUF.fold fld unf (defaultChunkSize, inh)
 
     where
 
@@ -181,7 +181,7 @@ inspect $ 'writeReadWithBufferOf `hasNoType` ''AT.ArrayUnsafe -- FH.write/writeN
 -- | Send the file contents ('AT.defaultChunkSize') to /dev/null
 {-# NOINLINE writeRead #-}
 writeRead :: Handle -> Handle -> IO ()
-writeRead inh devNull = IUF.fold unf fld inh
+writeRead inh devNull = IUF.fold fld unf inh
 
     where
 

benchmark/Streamly/Benchmark/Prelude/Serial/Exceptions.hs

@@ -135,7 +135,7 @@ o_1_space_copy_stream_exceptions env =
 readChunksOnException :: Handle -> Handle -> IO ()
 readChunksOnException inh devNull =
     let readEx = IUF.onException (\_ -> hClose inh) FH.readChunks
-    in IUF.fold readEx (IFH.writeChunks devNull) inh
+    in IUF.fold (IFH.writeChunks devNull) readEx inh
 
 #ifdef INSPECTION
 inspect $ hasNoTypeClasses 'readChunksOnException
@@ -146,7 +146,7 @@ inspect $ hasNoTypeClasses 'readChunksOnException
 readChunksBracket_ :: Handle -> Handle -> IO ()
 readChunksBracket_ inh devNull =
     let readEx = IUF.bracket_ return (\_ -> hClose inh) FH.readChunks
-    in IUF.fold readEx (IFH.writeChunks devNull) inh
+    in IUF.fold (IFH.writeChunks devNull) readEx inh
 
 #ifdef INSPECTION
 inspect $ hasNoTypeClasses 'readChunksBracket_
@@ -156,7 +156,7 @@ inspect $ hasNoTypeClasses 'readChunksBracket_
 readChunksBracket :: Handle -> Handle -> IO ()
 readChunksBracket inh devNull =
     let readEx = IUF.bracket return (\_ -> hClose inh) FH.readChunks
-    in IUF.fold readEx (IFH.writeChunks devNull) inh
+    in IUF.fold (IFH.writeChunks devNull) readEx inh
 
 o_1_space_copy_exceptions_readChunks :: BenchEnv -> [Benchmark]
 o_1_space_copy_exceptions_readChunks env =

src/Streamly/Internal/Data/Unfold.hs

@@ -328,8 +328,8 @@ swap = lmap Tuple.swap
 -- /Pre-release/
 --
 {-# INLINE_NORMAL fold #-}
-fold :: Monad m => Unfold m a b -> Fold m b c -> a -> m c
-fold (Unfold ustep inject) (Fold fstep initial extract) a = do
+fold :: Monad m => Fold m b c -> Unfold m a b -> a -> m c
+fold (Fold fstep initial extract) (Unfold ustep inject) a = do
     res <- initial
     case res of
         FL.Partial x -> inject a >>= go SPEC x