Merge pull request #18 from sid-kap/text_lines

Add readFileLines function

1 files changed, 22 insertions, 0 deletions

diff --git a/Pipes/Text/IO.hs b/Pipes/Text/IO.hs
index b7ef5cd..51c6926 100644
--- a/Pipes/Text/IO.hs
+++ b/Pipes/Text/IO.hs
@@ -11,8 +11,10 @@ module Pipes.Text.IO
    
    -- * Producers
    fromHandle
+   , fromHandleLn
    , stdin
    , readFile
+   , readFileLn
    -- * Consumers
    , toHandle
    , stdout
@@ -119,6 +121,19 @@ fromHandle h =  go where
                                     go 
 {-# INLINABLE fromHandle#-}
 
+
+fromHandleLn :: MonadIO m => IO.Handle -> Producer Text m ()
+fromHandleLn h =  go where
+      getLine :: IO (Either G.IOException Text)
+      getLine = try (T.hGetLine h)
+
+      go = do txt <- liftIO getLine
+              case txt of
+                Left e  -> return ()
+                Right y -> do yield y
+                              go
+{-# INLINABLE fromHandleLn #-}
+
 -- | Stream text from 'stdin'
 stdin :: MonadIO m => Producer Text m ()
 stdin = fromHandle IO.stdin
@@ -136,6 +151,13 @@ readFile file = Safe.withFile file IO.ReadMode fromHandle
 {-# INLINE readFile #-}
 
 
+{-| Stream lines of text from a file
+-}
+readFileLn :: MonadSafe m => FilePath -> Producer Text m ()
+readFileLn file = Safe.withFile file IO.ReadMode fromHandleLn
+{-# INLINE readFileLn #-}
+
+
 {-| Stream text to 'stdout'
 
     Unlike 'toHandle', 'stdout' gracefully terminates on a broken output pipe.