[project @ 1998-03-06 17:40:11 by simonpj]

[ghc-hetmet.git] / ghc / compiler / utils / Bag.lhs

diff --git a/ghc/compiler/utils/Bag.lhs b/ghc/compiler/utils/Bag.lhs
index 546ad2f..fe27061 100644 (file)
--- a/ghc/compiler/utils/Bag.lhs
+++ b/ghc/compiler/utils/Bag.lhs
@@ -10,7 +10,7 @@ module Bag (
        emptyBag, unitBag, unionBags, unionManyBags,
        mapBag,
        elemBag,
-       filterBag, partitionBag, concatBag, foldBag, foldrBag,
+       filterBag, partitionBag, concatBag, foldBag, foldrBag, foldlBag,
        isEmptyBag, consBag, snocBag,
        listToBag, bagToList
     ) where
@@ -130,6 +130,16 @@ foldrBag k z (TwoBags b1 b2) = foldrBag k (foldrBag k z b2) b1
 foldrBag k z (ListBag xs)    = foldr k z xs
 foldrBag k z (ListOfBags bs) = foldr (\b r -> foldrBag k r b) z bs
 
+foldlBag :: (r -> a -> r) -> r
+        -> Bag a
+        -> r
+
+foldlBag k z EmptyBag        = z
+foldlBag k z (UnitBag x)     = k z x
+foldlBag k z (TwoBags b1 b2) = foldlBag k (foldlBag k z b1) b2
+foldlBag k z (ListBag xs)    = foldl k z xs
+foldlBag k z (ListOfBags bs) = foldl (\r b -> foldlBag k r b) z bs
+
 
 mapBag :: (a -> b) -> Bag a -> Bag b
 mapBag f EmptyBag       = EmptyBag