diff options
Diffstat (limited to 'compiler/GHC/Data/Bag.hs')
| -rw-r--r-- | compiler/GHC/Data/Bag.hs | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/compiler/GHC/Data/Bag.hs b/compiler/GHC/Data/Bag.hs index 5ace42ba13..a9b8a669de 100644 --- a/compiler/GHC/Data/Bag.hs +++ b/compiler/GHC/Data/Bag.hs @@ -19,7 +19,7 @@ module GHC.Data.Bag ( isEmptyBag, isSingletonBag, consBag, snocBag, anyBag, allBag, listToBag, nonEmptyToBag, bagToList, headMaybe, mapAccumBagL, concatMapBag, concatMapBagPair, mapMaybeBag, unzipBag, - mapBagM, mapBagM_, + mapBagM, mapBagM_, lookupBag, flatMapBagM, flatMapBagPairM, mapAndUnzipBagM, mapAccumBagLM, anyBagM, filterBagM @@ -38,6 +38,7 @@ import Data.List ( partition, mapAccumL ) import Data.List.NonEmpty ( NonEmpty(..) ) import qualified Data.List.NonEmpty as NE import qualified Data.Semigroup ( (<>) ) +import Control.Applicative( Alternative( (<|>) ) ) infixr 3 `consBag` infixl 3 `snocBag` @@ -115,6 +116,16 @@ filterBagM pred (ListBag vs) = do sat <- filterM pred (toList vs) return (listToBag sat) +lookupBag :: Eq a => a -> Bag (a,b) -> Maybe b +lookupBag _ EmptyBag = Nothing +lookupBag k (UnitBag kv) = lookup_one k kv +lookupBag k (TwoBags b1 b2) = lookupBag k b1 <|> lookupBag k b2 +lookupBag k (ListBag xs) = foldr ((<|>) . lookup_one k) Nothing xs + +lookup_one :: Eq a => a -> (a,b) -> Maybe b +lookup_one k (k',v) | k==k' = Just v + | otherwise = Nothing + allBag :: (a -> Bool) -> Bag a -> Bool allBag _ EmptyBag = True allBag p (UnitBag v) = p v |