X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Control%2FConcurrent%2FChan.hs;h=12f75c997c42d26431c8ded13d09b8556630ea6d;hb=2b2397221c29a275630c62d4982caedc2c7cd987;hp=1fca981077bae5071e50d79ba03b8b42edf726c3;hpb=2570f264ed329f04017d507250494eb0ab680d64;p=ghc-base.git

diff --git a/Control/Concurrent/Chan.hs b/Control/Concurrent/Chan.hs
index 1fca981..12f75c9 100644
--- a/Control/Concurrent/Chan.hs
+++ b/Control/Concurrent/Chan.hs
@@ -14,25 +14,25 @@
 
 module Control.Concurrent.Chan
   ( 
-	  -- * The 'Chan' type
-	Chan,			-- abstract
-
-	  -- * Operations
-	newChan,	 	-- :: IO (Chan a)
-	writeChan,	 	-- :: Chan a -> a -> IO ()
-	readChan,	 	-- :: Chan a -> IO a
-	dupChan,	 	-- :: Chan a -> IO (Chan a)
-	unGetChan,		-- :: Chan a -> a -> IO ()
-	isEmptyChan,		-- :: Chan a -> IO Bool
-
-	  -- * Stream interface
-	getChanContents,	-- :: Chan a -> IO [a]
-	writeList2Chan,		-- :: Chan a -> [a] -> IO ()
+          -- * The 'Chan' type
+        Chan,                   -- abstract
+
+          -- * Operations
+        newChan,                -- :: IO (Chan a)
+        writeChan,              -- :: Chan a -> a -> IO ()
+        readChan,               -- :: Chan a -> IO a
+        dupChan,                -- :: Chan a -> IO (Chan a)
+        unGetChan,              -- :: Chan a -> a -> IO ()
+        isEmptyChan,            -- :: Chan a -> IO Bool
+
+          -- * Stream interface
+        getChanContents,        -- :: Chan a -> IO [a]
+        writeList2Chan,         -- :: Chan a -> [a] -> IO ()
    ) where
 
 import Prelude
 
-import System.IO.Unsafe		( unsafeInterleaveIO )
+import System.IO.Unsafe         ( unsafeInterleaveIO )
 import Control.Concurrent.MVar
 import Data.Typeable
 
@@ -63,9 +63,9 @@ data ChItem a = ChItem a (Stream a)
 newChan :: IO (Chan a)
 newChan = do
    hole  <- newEmptyMVar
-   read  <- newMVar hole
-   write <- newMVar hole
-   return (Chan read write)
+   readVar  <- newMVar hole
+   writeVar <- newMVar hole
+   return (Chan readVar writeVar)
 
 -- To put an element on a channel, a new hole at the write end is created.
 -- What was previously the empty @MVar@ at the back of the channel is then
@@ -74,19 +74,19 @@ newChan = do
 
 -- |Write a value to a 'Chan'.
 writeChan :: Chan a -> a -> IO ()
-writeChan (Chan _read write) val = do
+writeChan (Chan _ writeVar) val = do
   new_hole <- newEmptyMVar
-  modifyMVar_ write $ \old_hole -> do
+  modifyMVar_ writeVar $ \old_hole -> do
     putMVar old_hole (ChItem val new_hole)
     return new_hole
 
 -- |Read the next value from the 'Chan'.
 readChan :: Chan a -> IO a
-readChan (Chan read _write) = do
-  modifyMVar read $ \read_end -> do
+readChan (Chan readVar _) = do
+  modifyMVar readVar $ \read_end -> do
     (ChItem val new_read_end) <- readMVar read_end
-	-- Use readMVar here, not takeMVar,
-	-- else dupChan doesn't work
+        -- Use readMVar here, not takeMVar,
+        -- else dupChan doesn't work
     return (new_read_end, val)
 
 -- |Duplicate a 'Chan': the duplicate channel begins empty, but data written to
@@ -94,24 +94,24 @@ readChan (Chan read _write) = do
 -- a kind of broadcast channel, where data written by anyone is seen by
 -- everyone else.
 dupChan :: Chan a -> IO (Chan a)
-dupChan (Chan _read write) = do
-   hole     <- readMVar write
-   new_read <- newMVar hole
-   return (Chan new_read write)
+dupChan (Chan _ writeVar) = do
+   hole       <- readMVar writeVar
+   newReadVar <- newMVar hole
+   return (Chan newReadVar writeVar)
 
 -- |Put a data item back onto a channel, where it will be the next item read.
 unGetChan :: Chan a -> a -> IO ()
-unGetChan (Chan read _write) val = do
+unGetChan (Chan readVar _) val = do
    new_read_end <- newEmptyMVar
-   modifyMVar_ read $ \read_end -> do
+   modifyMVar_ readVar $ \read_end -> do
      putMVar new_read_end (ChItem val read_end)
      return new_read_end
 
 -- |Returns 'True' if the supplied 'Chan' is empty.
 isEmptyChan :: Chan a -> IO Bool
-isEmptyChan (Chan read write) = do
-   withMVar read $ \r -> do
-     w <- readMVar write
+isEmptyChan (Chan readVar writeVar) = do
+   withMVar readVar $ \r -> do
+     w <- readMVar writeVar
      let eq = r == w
      eq `seq` return eq
 
@@ -122,9 +122,9 @@ isEmptyChan (Chan read write) = do
 getChanContents :: Chan a -> IO [a]
 getChanContents ch
   = unsafeInterleaveIO (do
-	x  <- readChan ch
-    	xs <- getChanContents ch
-    	return (x:xs)
+        x  <- readChan ch
+        xs <- getChanContents ch
+        return (x:xs)
     )
 
 -- |Write an entire list of items to a 'Chan'.