added lazy streamLn

src/Data/Text/Internal/Fusion.hs

@@ -79,7 +79,7 @@ stream ::
   HasCallStack =>
 #endif
   Text -> Stream Char
-stream t = stream' t False
+stream = stream' False
 {-# INLINE [0] stream #-}
 
 -- | /O(n)/ @'streamLn' t = 'stream' (t <> \'\\n\')@
@@ -90,15 +90,15 @@ streamLn ::
   HasCallStack =>
 #endif
   Text -> Stream Char
-streamLn t = stream' t True
+streamLn = stream' True
 
 -- | Shared implementation of 'stream' and 'streamLn'.
 stream' ::
 #if defined(ASSERTS)
   HasCallStack =>
 #endif
-  Text -> Bool -> Stream Char
-stream' (Text arr off len) addNl = Stream next off (betweenSize (len `shiftR` 2) maxLen)
+  Bool -> Text -> Stream Char
+stream' addNl (Text arr off len) = Stream next off (betweenSize (len `shiftR` 2) maxLen)
     where
       maxLen = if addNl then len + 1 else len
       !end = off+len

src/Data/Text/Internal/Lazy/Fusion.hs

@@ -17,6 +17,7 @@
 module Data.Text.Internal.Lazy.Fusion
     (
       stream
+    , streamLn
     , unstream
     , unstreamChunks
     , length
@@ -47,14 +48,35 @@ stream ::
   HasCallStack =>
 #endif
   Text -> Stream Char
-stream text = Stream next (text :*: 0) unknownSize
+stream = stream' False
+{-# INLINE [0] stream #-}
+
+-- | /O(n)/ @'streamLn' t = 'stream' (t <> \'\\n\')@
+--
+-- @since ????
+streamLn ::
+#if defined(ASSERTS)
+  HasCallStack =>
+#endif
+  Text -> Stream Char
+streamLn = stream' True
+
+-- | Shared implementation of 'stream' and 'streamLn'.
+stream' ::
+#if defined(ASSERTS)
+  HasCallStack =>
+#endif
+  Bool -> Text -> Stream Char
+stream' addNl text = Stream next (text :*: 0) unknownSize
   where
-    next (Empty :*: _) = Done
+    next (Empty :*: i)
+        | addNl && i <= 0 = Yield '\n' (Empty :*: 1)
+        | otherwise = Done
     next (txt@(Chunk t@(I.Text _ _ len) ts) :*: i)
         | i >= len  = next (ts :*: 0)
         | otherwise = Yield c (txt :*: i+d)
         where Iter c d = iter t i
-{-# INLINE [0] stream #-}
+{-# INLINE [0] stream' #-}
 
 -- | /O(n)/ Convert a 'Stream Char' into a 'Text', using the given
 -- chunk size.

src/Data/Text/Lazy/IO.hs

@@ -41,16 +41,15 @@ module Data.Text.Lazy.IO
 import Data.Text.Lazy (Text)
 import Prelude hiding (appendFile, getContents, getLine, interact,
                        putStr, putStrLn, readFile, writeFile)
-import System.IO (Handle, IOMode(..), hPutChar, openFile, stdin, stdout,
+import System.IO (Handle, IOMode(..), openFile, stdin, stdout,
                   withFile)
-import qualified Data.Text.IO as T
 import qualified Data.Text.Lazy as L
 import qualified Control.Exception as E
 import Control.Monad (when)
 import Data.IORef (readIORef)
 import Data.Text.Internal.IO (hGetLineWith, readChunk, hPutStream)
-import Data.Text.Internal.Lazy (Text(..), chunk, empty)
-import Data.Text.Internal.Lazy.Fusion (stream)
+import Data.Text.Internal.Lazy (chunk, empty)
+import Data.Text.Internal.Lazy.Fusion (stream, streamLn)
 import GHC.IO.Buffer (isEmptyBuffer)
 import GHC.IO.Exception (IOException(..), IOErrorType(..), ioException)
 import GHC.IO.Handle.Internals (augmentIOError, hClose_help,
@@ -134,9 +133,7 @@ hPutStr h = hPutStream h . stream
 
 -- | Write a string to a handle, followed by a newline.
 hPutStrLn :: Handle -> Text -> IO ()
-hPutStrLn h Empty = hPutChar h '\n'
-hPutStrLn h (Chunk t Empty) = T.hPutStrLn h t  -- print the newline after the last chunk atomically
-hPutStrLn h t = hPutStream h (stream t) >> hPutChar h '\n'
+hPutStrLn h t = hPutStream h $ streamLn t
 
 -- | The 'interact' function takes a function of type @Text -> Text@
 -- as its argument. The entire input from the standard input device is