X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcRnMonad.lhs;h=8d9273750e33b7d562c70801449d29754d114170;hb=f670c47f9f93ffd6d06b331cd40554cd5e92484c;hp=386eae8bf3f0707f20a4f79d3179548c0b95f655;hpb=aa0c0de94e25aa64139688f8e4c4ba51ddca6f54;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcRnMonad.lhs b/compiler/typecheck/TcRnMonad.lhs
index 386eae8..8d92737 100644
--- a/compiler/typecheck/TcRnMonad.lhs
+++ b/compiler/typecheck/TcRnMonad.lhs
@@ -257,29 +257,28 @@ getEpsVar = do { env <- getTopEnv; return (hsc_EPS env) }
 getEps :: TcRnIf gbl lcl ExternalPackageState
 getEps = do { env <- getTopEnv; readMutVar (hsc_EPS env) }
 
--- Updating the EPS.  This should be an atomic operation.
--- Note the delicate 'seq' which forces the EPS before putting it in the
--- variable.  Otherwise what happens is that we get
---	write eps_var (....(unsafeRead eps_var)....)
--- and if the .... is strict, that's obviously bottom.  By forcing it beforehand
--- we make the unsafeRead happen before we update the variable.
-
+-- | Update the external package state.  Returns the second result of the
+-- modifier function.
+--
+-- This is an atomic operation and forces evaluation of the modified EPS in
+-- order to avoid space leaks.
 updateEps :: (ExternalPackageState -> (ExternalPackageState, a))
 	  -> TcRnIf gbl lcl a
-updateEps upd_fn = do	{ traceIf (text "updating EPS")
-			; eps_var <- getEpsVar
-			; eps <- readMutVar eps_var
-			; let { (eps', val) = upd_fn eps }
-			; seq eps' (writeMutVar eps_var eps')
-			; return val }
+updateEps upd_fn = do
+  traceIf (text "updating EPS")
+  eps_var <- getEpsVar
+  atomicUpdMutVar' eps_var upd_fn
 
+-- | Update the external package state.
+--
+-- This is an atomic operation and forces evaluation of the modified EPS in
+-- order to avoid space leaks.
 updateEps_ :: (ExternalPackageState -> ExternalPackageState)
 	   -> TcRnIf gbl lcl ()
-updateEps_ upd_fn = do	{ traceIf (text "updating EPS_")
-			; eps_var <- getEpsVar
-			; eps <- readMutVar eps_var
-			; let { eps' = upd_fn eps }
-			; seq eps' (writeMutVar eps_var eps') }
+updateEps_ upd_fn = do
+  traceIf (text "updating EPS_")
+  eps_var <- getEpsVar
+  atomicUpdMutVar' eps_var (\eps -> (upd_fn eps, ()))
 
 getHpt :: TcRnIf gbl lcl HomePackageTable
 getHpt = do { env <- getTopEnv; return (hsc_HPT env) }