+getFileName :: TM FastString
+getFileName = fileName `liftM` getEnv
+
+sameFileName :: SrcSpan -> TM a -> TM a -> TM a
+sameFileName pos out_of_scope in_scope = do
+ file_name <- getFileName
+ case optSrcSpanFileName pos of
+ Just file_name2
+ | file_name == file_name2 -> in_scope
+ _ -> out_of_scope
+