diff options
Diffstat (limited to 'compiler/utils/Bag.hs')
| -rw-r--r-- | compiler/utils/Bag.hs | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/compiler/utils/Bag.hs b/compiler/utils/Bag.hs index 41c80390cc..2105eefc71 100644 --- a/compiler/utils/Bag.hs +++ b/compiler/utils/Bag.hs @@ -6,7 +6,7 @@ Bag: an unordered collection with duplicates -} -{-# LANGUAGE ScopedTypeVariables, CPP #-} +{-# LANGUAGE ScopedTypeVariables, CPP, DeriveFunctor #-} module Bag ( Bag, -- abstract type @@ -45,6 +45,7 @@ data Bag a | UnitBag a | TwoBags (Bag a) (Bag a) -- INVARIANT: neither branch is empty | ListBag [a] -- INVARIANT: the list is non-empty + deriving (Functor) emptyBag :: Bag a emptyBag = EmptyBag @@ -221,10 +222,7 @@ foldlBagM k z (TwoBags b1 b2) = do { z' <- foldlBagM k z b1; foldlBagM k z' b2 } foldlBagM k z (ListBag xs) = foldlM k z xs mapBag :: (a -> b) -> Bag a -> Bag b -mapBag _ EmptyBag = EmptyBag -mapBag f (UnitBag x) = UnitBag (f x) -mapBag f (TwoBags b1 b2) = TwoBags (mapBag f b1) (mapBag f b2) -mapBag f (ListBag xs) = ListBag (map f xs) +mapBag = fmap concatMapBag :: (a -> Bag b) -> Bag a -> Bag b concatMapBag _ EmptyBag = EmptyBag @@ -344,8 +342,5 @@ instance Data a => Data (Bag a) where dataTypeOf _ = mkNoRepType "Bag" dataCast1 x = gcast1 x -instance Functor Bag where - fmap = mapBag - instance Foldable.Foldable Bag where foldr = foldrBag |