From 1b07fb994363495a102d6b86a5f847a771a6f3b9 Mon Sep 17 00:00:00 2001
From: Luke Hoersten <luke@hoersten.org>
Date: Thu, 18 Dec 2014 11:43:53 -0600
Subject: Added some functions to help exposed chans to streams.

---
 src/System/IO/Streams/Concurrent/Unagi.hs | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

(limited to 'src/System/IO/Streams/Concurrent/Unagi.hs')

diff --git a/src/System/IO/Streams/Concurrent/Unagi.hs b/src/System/IO/Streams/Concurrent/Unagi.hs
index 7ee3fd5..141902f 100644
--- a/src/System/IO/Streams/Concurrent/Unagi.hs
+++ b/src/System/IO/Streams/Concurrent/Unagi.hs
@@ -6,13 +6,16 @@ module System.IO.Streams.Concurrent.Unagi
        , chanToInput
        , chanToOutput
        , makeChanPipe
+       , chanToPipe
+       , dupStream
        ) where
 
 
 ------------------------------------------------------------------------------
 import           Control.Applicative           ((<$>), (<*>))
-import           Control.Concurrent.Chan.Unagi (InChan, OutChan, newChan,
-                                                readChan, writeChan)
+import           Control.Concurrent.Chan.Unagi (InChan, OutChan, dupChan,
+                                                newChan, readChan, writeChan)
+import           Control.Monad                 ((>=>))
 import           Prelude                       hiding (read)
 import           System.IO.Streams.Internal    (InputStream, OutputStream,
                                                 makeInputStream,
@@ -56,3 +59,20 @@ makeChanPipe :: IO (InputStream a, OutputStream a)
 makeChanPipe = do
     (inChan, outChan) <- newChan
     (,) <$> chanToInput outChan <*> chanToOutput inChan
+
+
+--------------------------------------------------------------------------------
+-- | Create a new pair of streams form the given 'Chan'. Everything written
+-- to the 'OutputStream' will appear as-is on the 'InputStream'.
+--
+-- Since reading from the 'InputStream' and writing to the 'OutputStream' are
+-- blocking calls, be sure to do so in different threads.
+chanToPipe :: (InChan (Maybe a), OutChan (Maybe a)) -> IO (InputStream a, OutputStream a)
+chanToPipe (inChan, outChan) = (,) <$> chanToInput outChan <*> chanToOutput inChan
+
+
+--------------------------------------------------------------------------------
+-- | Create a new input stream duplicated from the 'InChan'
+--
+dupStream :: InChan (Maybe a) -> IO (InputStream a)
+dupStream = dupChan >=> chanToInput
-- 
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