An implementation of a zipperlike nonempty list structure that tracks
an index position in the list (the focus
).
 data PointedList a = PointedList {
 reversedPrefix :: [a]
 _focus :: a
 suffix :: [a]
 lSuffix :: forall (~>) a. Arrow ~> => Lens ~> (PointedList a) [a]
 lReversedPrefix :: forall (~>) a. Arrow ~> => Lens ~> (PointedList a) [a]
 focus :: forall (~>) a. Arrow ~> => Lens ~> (PointedList a) a
 singleton :: a > PointedList a
 fromList :: [a] > Maybe (PointedList a)
 fromListEnd :: [a] > Maybe (PointedList a)
 replace :: a > PointedList a > PointedList a
 next :: PointedList a > Maybe (PointedList a)
 tryNext :: PointedList a > PointedList a
 previous :: PointedList a > Maybe (PointedList a)
 tryPrevious :: PointedList a > PointedList a
 insert :: a > PointedList a > PointedList a
 insertLeft :: a > PointedList a > PointedList a
 insertRight :: a > PointedList a > PointedList a
 delete :: PointedList a > Maybe (PointedList a)
 deleteLeft :: PointedList a > Maybe (PointedList a)
 deleteRight :: PointedList a > Maybe (PointedList a)
 deleteOthers :: PointedList a > PointedList a
 length :: PointedList a > Int
 atStart :: PointedList a > Bool
 atEnd :: PointedList a > Bool
 positions :: PointedList a > PointedList (PointedList a)
 contextMap :: (PointedList a > b) > PointedList a > PointedList b
 withFocus :: PointedList a > PointedList (a, Bool)
 moveTo :: Int > PointedList a > Maybe (PointedList a)
 moveN :: Int > PointedList a > Maybe (PointedList a)
 find :: Eq a => a > PointedList a > Maybe (PointedList a)
 index :: PointedList a > Int
Documentation
data PointedList a Source
The implementation of the pointed list structure which tracks the current position in the list structure.
PointedList  

Functor PointedList  
Foldable PointedList  
Traversable PointedList  
Eq a => Eq (PointedList a)  
Show a => Show (PointedList a)  
Binary a_1627403032 => Binary (PointedList a_1627403032) 
lSuffix :: forall (~>) a. Arrow ~> => Lens ~> (PointedList a) [a]Source
lReversedPrefix :: forall (~>) a. Arrow ~> => Lens ~> (PointedList a) [a]Source
focus :: forall (~>) a. Arrow ~> => Lens ~> (PointedList a) aSource
singleton :: a > PointedList aSource
Create a PointedList
with a single element.
fromList :: [a] > Maybe (PointedList a)Source
Possibly create a
if the provided list has at least
one element; otherwise, return Nothing.
Just
PointedList
The provided list's head will be the focus of the list, and the rest of list will follow on the right side.
fromListEnd :: [a] > Maybe (PointedList a)Source
Possibly create a
if the provided list has at least
one element; otherwise, return Nothing.
Just
PointedList
The provided list's last element will be the focus of the list, following the rest of the list in order, to the left.
replace :: a > PointedList a > PointedList aSource
Replace the focus of the list, retaining the prefix and suffix.
next :: PointedList a > Maybe (PointedList a)Source
Possibly move the focus to the next element in the list.
tryNext :: PointedList a > PointedList aSource
Attempt to move the focus to the next element, or error
if there are
no more elements.
previous :: PointedList a > Maybe (PointedList a)Source
Possibly move the focus to the previous element in the list.
tryPrevious :: PointedList a > PointedList aSource
Attempt to move the focus to the previous element, or error
if there are
no more elements.
insert :: a > PointedList a > PointedList aSource
An alias for insertRight
.
insertLeft :: a > PointedList a > PointedList aSource
Insert an element to the left of the focus, then move the focus to the new element.
insertRight :: a > PointedList a > PointedList aSource
Insert an element to the right of the focus, then move the focus to the new element.
delete :: PointedList a > Maybe (PointedList a)Source
An alias of deleteRight
.
deleteLeft :: PointedList a > Maybe (PointedList a)Source
Possibly delete the element at the focus, then move the element on the
left to the focus. If no element is on the left, focus on the element to
the right. If the deletion will cause the list to be empty, return
Nothing
.
deleteRight :: PointedList a > Maybe (PointedList a)Source
Possibly delete the element at the focus, then move the element on the
right to the focus. If no element is on the right, focus on the element to
the left. If the deletion will cause the list to be empty, return
Nothing
.
deleteOthers :: PointedList a > PointedList aSource
Delete all elements in the list except the focus.
length :: PointedList a > IntSource
The length of the list.
atStart :: PointedList a > BoolSource
Whether the focus is the first element.
atEnd :: PointedList a > BoolSource
Whether the focus is the last element.
positions :: PointedList a > PointedList (PointedList a)Source
Create a PointedList
of variations of the provided PointedList
, in
which each element is focused, with the provided PointedList
as the
focus of the sets.
contextMap :: (PointedList a > b) > PointedList a > PointedList bSource
Map over the PointedList
s created via positions
, such that f
is
called with each element of the list focused in the provided
PointedList
. An example makes this easier to understand:
contextMap atStart (fromJust $ fromList [1..5])
withFocus :: PointedList a > PointedList (a, Bool)Source
Create a
of PointedList
a(a,
, in which the boolean values
specify whether the current element has the focus. That is, all of the
booleans will be Bool
)False
, except the focused element.
moveTo :: Int > PointedList a > Maybe (PointedList a)Source
Move the focus to the specified index. The first element is at index 0.
moveN :: Int > PointedList a > Maybe (PointedList a)Source
Move the focus by n
, relative to the current index. Negative values move
the focus backwards, positive values more forwards through the list.
find :: Eq a => a > PointedList a > Maybe (PointedList a)Source
Move the focus to the specified element, if it is present.
Patch with much faster algorithm provided by Runar Bjarnason for version 0.3.2. Improved again by Runar Bjarnason for version 0.3.3 to support infinite lists on both sides of the focus.
index :: PointedList a > IntSource
The index of the focus, leftmost is 0.