[project @ 2002-07-04 13:06:28 by simonpj]

[ghc-hetmet.git] / ghc / compiler / typecheck / TcMatches.lhs

diff --git a/ghc/compiler/typecheck/TcMatches.lhs b/ghc/compiler/typecheck/TcMatches.lhs
index f8f2f4b..516c822 100644 (file)
--- a/ghc/compiler/typecheck/TcMatches.lhs
+++ b/ghc/compiler/typecheck/TcMatches.lhs
@@ -39,7 +39,7 @@ import BasicTypes     ( RecFlag(..) )
 import VarSet
 import Var             ( Id )
 import Bag
-import Util            ( isSingleton, lengthExceeds )
+import Util            ( isSingleton, lengthExceeds, notNull )
 import Outputable
 
 import List            ( nub )
@@ -302,7 +302,7 @@ tcCheckExistentialPat ex_tvs ex_ids ex_lie lie_req match_ty
 
     returnTc (lie2, dict_binds `AndMonoBinds` inst_binds)
   where
-    doc     = text ("the existential context of a data constructor")
+    doc     = text ("existential context of a data constructor")
     tv_list = bagToList ex_tvs
     not_overloaded id = not (isOverloadedTy (idType id))
 \end{code}
@@ -338,7 +338,8 @@ group.  But that's fine; there's no shadowing to worry about.
 
 \begin{code}
 tcStmts do_or_lc m_ty stmts
-  = tcStmtsAndThen (:) do_or_lc m_ty stmts (returnTc ([], emptyLIE))
+  = ASSERT( notNull stmts )
+    tcStmtsAndThen (:) do_or_lc m_ty stmts (returnTc ([], emptyLIE))
 
 tcStmtsAndThen
        :: (TcStmt -> thing -> thing)   -- Combiner