diff --git a/ghc/lib/concurrent/Channel.lhs b/ghc/lib/concurrent/Channel.lhs
index ec874797d78c49c5b640c9cf3a54b6972cd12164..f9293c5e7602760f8170515d7323e5b13180ea8a 100644
--- a/ghc/lib/concurrent/Channel.lhs
+++ b/ghc/lib/concurrent/Channel.lhs
@@ -111,6 +111,6 @@ getChanContents ch
 
 -------------
 writeList2Chan :: Chan a -> [a] -> IO ()
-writeList2Chan ch ls = sequence (map (writeChan ch) ls)
+writeList2Chan ch ls = sequence_ (map (writeChan ch) ls)
 
 \end{code}
diff --git a/ghc/lib/concurrent/ChannelVar.lhs b/ghc/lib/concurrent/ChannelVar.lhs
index 5a7db0ec0130cfd5e0124c056c1d7045a43e3b35..50c893cb03a910a49d2c717a82c79dec76aa68c5 100644
--- a/ghc/lib/concurrent/ChannelVar.lhs
+++ b/ghc/lib/concurrent/ChannelVar.lhs
@@ -11,9 +11,9 @@ module ChannelVar
        (
 	 {- abstract -}
          CVar,
-	 newCVar,	--:: IO (CVar a)
-	 writeCVar,	--:: CVar a -> a -> IO ()
-	 readCVar,	--:: CVar a -> IO a
+	 newCVar,	-- :: IO (CVar a)
+	 writeCVar,	-- :: CVar a -> a -> IO ()
+	 readCVar,	-- :: CVar a -> IO a
 	 MVar
 
        ) where
diff --git a/ghc/lib/concurrent/Merge.lhs b/ghc/lib/concurrent/Merge.lhs
index 39f1c4ce2f974fce969842f30d889d9cd5f7d7ff..706f0e6dbec9bfeb517e19fadcb9453914fe2cbe 100644
--- a/ghc/lib/concurrent/Merge.lhs
+++ b/ghc/lib/concurrent/Merge.lhs
@@ -10,8 +10,8 @@ IO monad.
 module Merge
 
 	(
-	 mergeIO,	--:: [a]   -> [a] -> IO [a]
-	 nmergeIO	--:: [[a]] -> IO [a]
+	 mergeIO,	-- :: [a]   -> [a] -> IO [a]
+	 nmergeIO	-- :: [[a]] -> IO [a]
 	) where
 
 import Semaphore
diff --git a/ghc/lib/concurrent/SampleVar.lhs b/ghc/lib/concurrent/SampleVar.lhs
index 53199a6fb1012db3b87e97213937df16ef9cad78..75476b6d58918ca3a4766a7d09fa38651c07fe22 100644
--- a/ghc/lib/concurrent/SampleVar.lhs
+++ b/ghc/lib/concurrent/SampleVar.lhs
@@ -19,13 +19,13 @@ potentially, wakes up a blocked reader  (same as for @putMVar@ on empty @MVar@).
 \begin{code}
 module SampleVar
        (
-         SampleVar,         --:: type _ =
+         SampleVar,         -- :: type _ =
  
-	 newEmptySampleVar, --:: IO (SampleVar a)
-         newSampleVar,      --:: a -> IO (SampleVar a)
-	 emptySampleVar,    --:: SampleVar a -> IO ()
-	 readSampleVar,	    --:: SampleVar a -> IO a
-	 writeSampleVar	    --:: SampleVar a -> a -> IO ()
+	 newEmptySampleVar, -- :: IO (SampleVar a)
+         newSampleVar,      -- :: a -> IO (SampleVar a)
+	 emptySampleVar,    -- :: SampleVar a -> IO ()
+	 readSampleVar,	    -- :: SampleVar a -> IO a
+	 writeSampleVar	    -- :: SampleVar a -> a -> IO ()
 
        ) where
 
diff --git a/ghc/lib/concurrent/Semaphore.lhs b/ghc/lib/concurrent/Semaphore.lhs
index 9fc8a0b14868773829b6092c972467a801278dc8..e7bd0d418968fafa0e836297dde4e8d5aff126c6 100644
--- a/ghc/lib/concurrent/Semaphore.lhs
+++ b/ghc/lib/concurrent/Semaphore.lhs
@@ -11,15 +11,15 @@ module Semaphore
        {- abstract -}
        QSem,
 
-       newQSem,		--:: Int  -> IO QSem
-       waitQSem,	--:: QSem -> IO ()
-       signalQSem,	--:: QSem -> IO ()
+       newQSem,		-- :: Int  -> IO QSem
+       waitQSem,	-- :: QSem -> IO ()
+       signalQSem,	-- :: QSem -> IO ()
 
        {- abstract -}
        QSemN,
-       newQSemN,	--:: Int   -> IO QSemN
-       waitQSemN,	--:: QSemN -> Int -> IO ()
-       signalQSemN	--:: QSemN -> Int -> IO ()
+       newQSemN,	-- :: Int   -> IO QSemN
+       waitQSemN,	-- :: QSemN -> Int -> IO ()
+       signalQSemN	-- :: QSemN -> Int -> IO ()
 	
       ) where