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Added a mapMapWithKeyM function to Utils, and cleaned up some of the whitespace

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Neil Brown 2008-05-14 12:18:27 +00:00
parent e3bf321f33
commit e843ce5022
1 changed files with 14 additions and 7 deletions
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21
common/Utils.hs
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@ -194,7 +194,7 @@ liftF :: (MonadTrans t, Monad m) => (a -> m b) -> (a -> t m b)
liftF f x = lift (f x) liftF f x = lift (f x)
-- | Like the (.) operator, but for monads. -- | Like the (.) operator, but for monads.
(<.<) :: Monad m => (b -> m c) -> (a -> m b) -> (a -> m c) (<.<) :: Monad m => (b -> m c) -> (a -> m b) -> (a -> m c)
(<.<) f1 f0 x = f0 x >>= f1 (<.<) f1 f0 x = f0 x >>= f1
@ -220,7 +220,7 @@ product4 :: ([a],[b],[c],[d]) -> [(a,b,c,d)]
product4 (l0,l1,l2,l3) = [(x0,x1,x2,x3) | x0 <- l0, x1 <- l1, x2 <- l2, x3 <- l3] product4 (l0,l1,l2,l3) = [(x0,x1,x2,x3) | x0 <- l0, x1 <- l1, x2 <- l2, x3 <- l3]
-- | Given a list, produces all possible distinct pairings of the elements. -- | Given a list, produces all possible distinct pairings of the elements.
-- That is, for each pair returned, (A,B), B will not be the same element as A, and the pair (B,A) -- That is, for each pair returned, (A,B), B will not be the same element as A, and the pair (B,A)
-- will not be in the list. Note that this is not the same as B /= A; if the source list contains -- will not be in the list. Note that this is not the same as B /= A; if the source list contains
-- two equal items, the returned pairs will feature a pair such that B /= A. -- two equal items, the returned pairs will feature a pair such that B /= A.
allPairs :: [a] -> [(a,a)] allPairs :: [a] -> [(a,a)]
@ -258,7 +258,7 @@ arrayZipWith' :: (IArray a e, Ix i) => e -> (e -> e -> e) -> a i e -> a i e -> a
arrayZipWith' def f a0 a1 = simpleArray $ map (\i -> (i,f' i)) allIndexes arrayZipWith' def f a0 a1 = simpleArray $ map (\i -> (i,f' i)) allIndexes
where where
allIndexes = nub $ indices a0 ++ indices a1 allIndexes = nub $ indices a0 ++ indices a1
f' i = f (arrayLookupWithDefault def a0 i) (arrayLookupWithDefault def a1 i) f' i = f (arrayLookupWithDefault def a0 i) (arrayLookupWithDefault def a1 i)
-- | Zips two maps using the given function. -- | Zips two maps using the given function.
@ -268,7 +268,7 @@ zipMap :: Ord k => (Maybe v -> Maybe v' -> Maybe v'') -> Map.Map k v -> Map.Map
zipMap f xs ys = Map.fromList $ mapMaybe f' (Set.elems allKeys) zipMap f xs ys = Map.fromList $ mapMaybe f' (Set.elems allKeys)
where where
allKeys = Map.keysSet xs `Set.union` Map.keysSet ys allKeys = Map.keysSet xs `Set.union` Map.keysSet ys
f' k = transformMaybe ((,) k) $ f (Map.lookup k xs) (Map.lookup k ys) f' k = transformMaybe ((,) k) $ f (Map.lookup k xs) (Map.lookup k ys)
showMaybe :: (a -> String) -> Maybe a -> String showMaybe :: (a -> String) -> Maybe a -> String
@ -303,7 +303,14 @@ data DataBox = forall t. Data t => DataBox t
-- A version of mapM that acts on the values in maps. -- A version of mapM that acts on the values in maps.
mapMapM :: (Ord a, Monad m) => (b -> m c) -> Map.Map a b -> m (Map.Map a c) mapMapM :: (Ord a, Monad m) => (b -> m c) -> Map.Map a b -> m (Map.Map a c)
mapMapM f m = liftM Map.fromAscList $ mapM f' $ Map.toAscList m mapMapM f m = mapMapWithKeyM (const f) m
-- A version of mapM that acts on the values in maps.
mapMapWithKeyM :: (Ord a, Monad m) => (a -> b -> m c) -> Map.Map a b -> m (Map.Map a c)
mapMapWithKeyM f m = liftM Map.fromAscList $ mapM f' $ Map.toAscList m
where where
f' (x,y) = do y' <- f y f' (x,y) = do y' <- f x y
return (x, y') return (x, y')