X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypes%2FFunDeps.lhs;h=5ece0471884ec94b704736a60133a1328c7ce17f;hp=0d7eb24325a20892432dbb84d103b0c8246474bd;hb=1c64864faf17b32ecaefa37fe8aa8fac5304f830;hpb=9b8b019d635218d9b52ddf0f5ea2b168e6f69cf4

diff --git a/compiler/types/FunDeps.lhs b/compiler/types/FunDeps.lhs
index 0d7eb24..5ece047 100644
--- a/compiler/types/FunDeps.lhs
+++ b/compiler/types/FunDeps.lhs
@@ -222,7 +222,11 @@ NOTA BENE:
 improve inst_env preds
   = [ eqn | group <- equivClassesByUniq (predTyUnique . fst) (filterEqPreds preds),
 	    eqn   <- checkGroup inst_env group ]
-  where filterEqPreds = filter (not . isEqPred . fst)
+  where 
+    filterEqPreds = filter (not . isEqPred . fst)
+	-- Equality predicates don't have uniques
+	-- In any case, improvement *generates*, rather than
+	-- *consumes*, equality constraints
 
 ----------
 checkGroup :: (Class -> [Instance])