X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FdeSugar%2FMatchLit.lhs;h=50fec2fd12b88a2dcfb388a71feac469ad4c2867;hb=9ec880fcb29ff038bcc72d78bbe2fd6933566047;hp=2cdab30bf8b162c0059b9182b1eab6385bdfb7b7;hpb=90dc9026b091be5cca5da4c6cbd3713ecc493361;p=ghc-hetmet.git

diff --git a/compiler/deSugar/MatchLit.lhs b/compiler/deSugar/MatchLit.lhs
index 2cdab30..50fec2f 100644
--- a/compiler/deSugar/MatchLit.lhs
+++ b/compiler/deSugar/MatchLit.lhs
@@ -27,12 +27,10 @@ import TcType
 import Type
 import PrelNames
 import TysWiredIn
-import PrelNames
 import Unique
 import Literal
 import SrcLoc
 import Ratio
-import SrcLoc
 import Outputable
 import Util
 import FastString
@@ -183,7 +181,8 @@ matchLiterals :: [Id]
 	      -> DsM MatchResult
 
 matchLiterals (var:vars) ty sub_groups
-  = do	{	-- Deal with each group
+  = ASSERT( all notNull sub_groups )
+    do	{	-- Deal with each group
 	; alts <- mapM match_group sub_groups
 
 	 	-- Combine results.  For everything except String