Remove redundant "do", "return" and language extensions from base

4 files changed, 4 insertions, 4 deletions

diff --git a/libraries/base/Control/Concurrent/Chan.hs b/libraries/base/Control/Concurrent/Chan.hs
index 874e48a1a1..1599ae3048 100644
--- a/libraries/base/Control/Concurrent/Chan.hs
+++ b/libraries/base/Control/Concurrent/Chan.hs
@@ -105,7 +105,7 @@ writeChan (Chan _ writeVar) val = do
 -- Throws 'Control.Exception.BlockedIndefinitelyOnMVar' when the channel is
 -- empty and no other thread holds a reference to the channel.
 readChan :: Chan a -> IO a
-readChan (Chan readVar _) = do
+readChan (Chan readVar _) =
   modifyMVar readVar $ \read_end -> do
     (ChItem val new_read_end) <- readMVar read_end
         -- Use readMVar here, not takeMVar,
diff --git a/libraries/base/Control/Concurrent/QSem.hs b/libraries/base/Control/Concurrent/QSem.hs
index 133d6e2ab8..9f53eef826 100644
--- a/libraries/base/Control/Concurrent/QSem.hs
+++ b/libraries/base/Control/Concurrent/QSem.hs
@@ -82,7 +82,7 @@ waitQSem (QSem m) =
          putMVar m (z, b1, b2)
          return ()
   where
-    wait b = takeMVar b `onException` do
+    wait b = takeMVar b `onException`
                 (uninterruptibleMask_ $ do -- Note [signal uninterruptible]
                    (i,b1,b2) <- takeMVar m
                    r <- tryTakeMVar b
diff --git a/libraries/base/Control/Concurrent/QSemN.hs b/libraries/base/Control/Concurrent/QSemN.hs
index ea3236b0a4..1262198796 100644
--- a/libraries/base/Control/Concurrent/QSemN.hs
+++ b/libraries/base/Control/Concurrent/QSemN.hs
@@ -93,7 +93,7 @@ waitQSemN qs@(QSemN m) sz = mask_ $ do
     JustMV b -> wait b
   where
     wait :: MVar () -> IO ()
-    wait b = do
+    wait b =
       takeMVar b `onException` do
         already_filled <- not <$> tryPutMVar b ()
         when already_filled $ signalQSemN qs sz
diff --git a/libraries/base/Control/Monad/ST/Lazy/Imp.hs b/libraries/base/Control/Monad/ST/Lazy/Imp.hs
index db900d9579..de8310c76d 100644
--- a/libraries/base/Control/Monad/ST/Lazy/Imp.hs
+++ b/libraries/base/Control/Monad/ST/Lazy/Imp.hs
@@ -42,7 +42,7 @@ import Control.Monad.Fix
 import qualified Control.Monad.ST as ST
 import qualified Control.Monad.ST.Unsafe as ST
 
-import qualified GHC.ST as GHC.ST
+import qualified GHC.ST
 import GHC.Base
 
 -- | The lazy @'ST'@ monad.