Data.List.Zipper

Documentation

data Zipper a

Simple Zipper for Lists.

Constructors

Zipper [a] [a]

Instances

Functor Zipper

Defined in Data.List.Zipper

Methods

fmap :: (a -> b) -> Zipper a -> Zipper b

(<$) :: a -> Zipper b -> Zipper a

Foldable Zipper

Defined in Data.List.Zipper

Methods

fold :: Monoid m => Zipper m -> m

foldMap :: Monoid m => (a -> m) -> Zipper a -> m

foldr :: (a -> b -> b) -> b -> Zipper a -> b

foldr' :: (a -> b -> b) -> b -> Zipper a -> b

foldl :: (b -> a -> b) -> b -> Zipper a -> b

foldl' :: (b -> a -> b) -> b -> Zipper a -> b

foldr1 :: (a -> a -> a) -> Zipper a -> a

foldl1 :: (a -> a -> a) -> Zipper a -> a

toList :: Zipper a -> [a]

null :: Zipper a -> Bool

length :: Zipper a -> Int

elem :: Eq a => a -> Zipper a -> Bool

maximum :: Ord a => Zipper a -> a

minimum :: Ord a => Zipper a -> a

sum :: Num a => Zipper a -> a

product :: Num a => Zipper a -> a

Eq a => Eq (Zipper a)

Defined in Data.List.Zipper

Methods

(==) :: Zipper a -> Zipper a -> Bool

(/=) :: Zipper a -> Zipper a -> Bool

Show a => Show (Zipper a)

Defined in Data.List.Zipper

Methods

showsPrec :: Int -> Zipper a -> ShowS

show :: Zipper a -> String

showList :: [Zipper a] -> ShowS

fromList :: [a] -> Zipper a

Construct a Zipper from a list

running time: \(O(1)\)

goNext :: Zipper a -> Maybe (Zipper a)

Go to the Next Element

running time: \(O(1)\)

goPrev :: Zipper a -> Maybe (Zipper a)

Go to the previous Element

running time: \(O(1)\)

allNexts :: Zipper a -> [Zipper a]

Computes all nexts, even one that has no elements initially or at the end.

>>> mapM_ print $ allNexts $ fromList [1..5]
Zipper [] [1,2,3,4,5]
Zipper [1] [2,3,4,5]
Zipper [2,1] [3,4,5]
Zipper [3,2,1] [4,5]
Zipper [4,3,2,1] [5]
Zipper [5,4,3,2,1] []

extractNext :: Zipper a -> Maybe (a, Zipper a)

Returns the next element, and the zipper without it

dropNext :: Zipper a -> Maybe (Zipper a)

Drops the next element in the zipper.

running time: \(O(1)\)

allNonEmptyNexts :: Zipper a -> [Zipper a]

Computes all list that still have next elements.

>>> mapM_ print $ allNonEmptyNexts $ fromList [1..5]
Zipper [] [1,2,3,4,5]
Zipper [1] [2,3,4,5]
Zipper [2,1] [3,4,5]
Zipper [3,2,1] [4,5]
Zipper [4,3,2,1] [5]