2.5 KiB
2.5 KiB
Folds
Basic Folds
foldMap :: (Foldable t, Monoid m) => (a -> m) -> t a -> m
foldr :: Foldable t => (a -> b -> b) -> b -> t a -> b
foldl :: Foldable t => (b -> a -> b) -> b -> t a -> b
foldr' :: Foldable t => (a -> b -> b) -> b -> t a -> b
foldl' :: Foldable t => (b -> a -> b) -> b -> t a -> b
fold :: Foldable t => Monoid m => t m -> m
toList :: Foldable t => t a -> [a]
null :: Foldable t => t a -> Bool
length :: Foldable t => t a -> Int
elem :: (Eq a, Foldable t) => a -> t a -> Bool
maximum :: (Ord a, Foldable t) => t a -> a
minimum :: (Ord a, Foldable t) => t a -> a
sum :: (Num a, Foldable f) => f a -> a
product :: (Num a, Foldable f) => f a -> a
Folding actions
traverse_ :: (Foldable t, Applicative f) => (a -> f b) -> t a -> f ()
for_ :: (Foldable t, Applicative f) => t a -> (a -> f b) -> f ()
Example:
>>> for_ [1..4] print
1
2
3
4
Applicative Folds
sequenceA_ :: (Foldable t, Applicative f) => t (f a) -> f ()
asum :: (Foldable t, Alternative f) => t (f a) -> f a
Monadic Folds
mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m ()
forM_ :: (Foldable t, Monad m) => t a -> (a -> m b) -> m ()
sequence_ :: (Foldable t, Monad m) => t (m a) -> m ()
msum :: (Foldable t, MonadPlus m) => t (m a) -> m a
foldrM :: (Foldable t, Monad m) => (a -> b -> m b) -> b -> t a -> m b
foldlM :: (Foldable t, Monad m) => (b -> a -> m b) -> b -> t a -> m b
Specialized folds
concat :: Foldable t => t [a] -> [a]
concatMap :: Foldable t => (a -> [b]) -> t a -> [b]
and :: Foldable t => t Bool -> Bool
or :: Foldable t => t Bool -> Bool
any :: Foldable t => (a -> Bool) -> t a -> Bool
all :: Foldable t => (a -> Bool) -> t a -> Bool
maximumBy :: Foldable t => (a -> a -> Ordering) -> t a -> a
minimumBy :: Foldable t => (a -> a -> Ordering) -> t a -> a
Searches
notElem :: (Foldable t, Eq a) => a -> t a -> Bool
find :: Foldable t => (a -> Bool) -> t a -> Maybe a
foldr1May :: (a -> a -> a) -> [a] -> Maybe a
foldl1May :: (a -> a -> a) -> [a] -> Maybe a