diff options
| -rw-r--r-- | compiler/GHC/Data/Bag.hs | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/compiler/GHC/Data/Bag.hs b/compiler/GHC/Data/Bag.hs index 4171d7b03e..94a9ba86f8 100644 --- a/compiler/GHC/Data/Bag.hs +++ b/compiler/GHC/Data/Bag.hs @@ -74,7 +74,6 @@ unionManyBags xs = foldr unionBags EmptyBag xs unionBags :: Bag a -> Bag a -> Bag a unionBags EmptyBag b = b -unionBags b EmptyBag = b unionBags b1 b2 = TwoBags b1 b2 consBag :: a -> Bag a -> Bag a @@ -85,6 +84,8 @@ snocBag bag elt = bag `unionBags` (unitBag elt) isEmptyBag :: Bag a -> Bool isEmptyBag EmptyBag = True +isEmptyBag (TwoBags b1 b2) = isEmptyBag b1 && isEmptyBag b2 +isEmptyBag (ListBag xs) = null xs isEmptyBag _ = False -- NB invariants isSingletonBag :: Bag a -> Bool |