Drop System.Mem.Weak's dependency on Prelude

diff --git a/System/Mem/Weak.hs b/System/Mem/Weak.hs
index 208302f..61dce1d 100644 (file)
--- a/System/Mem/Weak.hs
+++ b/System/Mem/Weak.hs
@@ -67,13 +67,16 @@ module System.Mem.Weak (
        -- $precise
    ) where
 
-import Prelude
+import Data.Maybe (Maybe(..))
 
 #ifdef __HUGS__
 import Hugs.Weak
+import Prelude
 #endif
 
 #ifdef __GLASGOW_HASKELL__
+import GHC.Base (return)
+import GHC.Types (IO)
 import GHC.Weak
 #endif