-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | A zipper-like comonad which works as a list, tracking a position.
--   
--   A PointedList tracks the position in a non-empty list which works
--   similarly to a zipper. A current item is always required, and
--   therefore the list may never be empty. A circular PointedList wraps
--   around to the other end when progressing past the actual edge.
@package pointedlist
@version 0.3.3


-- | An implementation of a zipper-like non-empty list structure that
--   tracks an index position in the list (the <a>focus</a>).
module Data.List.PointedList

-- | The implementation of the pointed list structure which tracks the
--   current position in the list structure.
data PointedList a
PointedList :: [a] -> a -> [a] -> PointedList a

-- | Create a <tt>PointedList</tt> with a single element.
singleton :: a -> PointedList a

-- | Possibly create a <tt>Just PointedList</tt> if the provided list has
--   at least one element; otherwise, return Nothing.
--   
--   The provided list's head will be the focus of the list, and the rest
--   of list will follow on the right side.
fromList :: [a] -> Maybe (PointedList a)

-- | Possibly create a <tt>Just PointedList</tt> if the provided list has
--   at least one element; otherwise, return Nothing.
--   
--   The provided list's last element will be the focus of the list,
--   following the rest of the list in order, to the left.
fromListEnd :: [a] -> Maybe (PointedList a)

-- | The focus element of the pointed list.
focus :: PointedList a -> a

-- | Accessor to read and edit the focus.
focusA :: Accessor (PointedList a) a

-- | Possibly move the focus to the next element in the list.
next :: PointedList a -> Maybe (PointedList a)

-- | Attempt to move the focus to the next element, or <a>error</a> if
--   there are no more elements.
tryNext :: PointedList a -> PointedList a

-- | Possibly move the focus to the previous element in the list.
previous :: PointedList a -> Maybe (PointedList a)

-- | Attempt to move the focus to the previous element, or <a>error</a> if
--   there are no more elements.
tryPrevious :: PointedList a -> PointedList a

-- | An alias for <a>insertRight</a>.
insert :: a -> PointedList a -> PointedList a

-- | Insert an element to the left of the focus, then move the focus to the
--   new element.
insertLeft :: a -> PointedList a -> PointedList a

-- | Insert an element to the right of the focus, then move the focus to
--   the new element.
insertRight :: a -> PointedList a -> PointedList a

-- | An alias of <a>deleteRight</a>.
delete :: PointedList a -> Maybe (PointedList a)

-- | 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
--   <tt>Nothing</tt>.
deleteLeft :: PointedList a -> Maybe (PointedList a)

-- | 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 <tt>Nothing</tt>.
deleteRight :: PointedList a -> Maybe (PointedList a)

-- | Delete all elements in the list except the focus.
deleteOthers :: PointedList a -> PointedList a

-- | The length of the list.
length :: PointedList a -> Int

-- | Whether the focus is the first element.
atStart :: PointedList a -> Bool

-- | Whether the focus is the last element.
atEnd :: PointedList a -> Bool

-- | Create a <tt>PointedList</tt> of variations of the provided
--   <tt>PointedList</tt>, in which each element is focused, with the
--   provided <tt>PointedList</tt> as the focus of the sets.
positions :: PointedList a -> PointedList (PointedList a)

-- | Map over the <tt>PointedList</tt>s created via <a>positions</a>, such
--   that <tt>f</tt> is called with each element of the list focused in the
--   provided <tt>PointedList</tt>. An example makes this easier to
--   understand:
--   
--   <pre>
--   contextMap atStart (fromJust $ fromList [1..5])
--   </pre>
contextMap :: (PointedList a -> b) -> PointedList a -> PointedList b

-- | Create a <tt>PointedList a</tt> of <tt>(a, Bool)</tt>, in which the
--   boolean values specify whether the current element has the focus. That
--   is, all of the booleans will be <tt>False</tt>, except the focused
--   element.
withFocus :: PointedList a -> PointedList (a, Bool)

-- | Move the focus to the specified index.
move :: Int -> PointedList a -> Maybe (PointedList a)

-- | 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.
find :: (Eq a) => a -> PointedList a -> Maybe (PointedList a)

-- | The index of the focus.
index :: PointedList a -> Int
instance (Eq a) => Eq (PointedList a)
instance (Ord a) => Ord (PointedList a)
instance (Binary t1) => Binary (PointedList t1)
instance Traversable PointedList
instance Foldable PointedList
instance Functor PointedList
instance (Show a) => Show (PointedList a)

module Data.List.PointedList.Circular

-- | Move the focus to the next element in the list. If the last element is
--   currently focused, loop to the first element.
next :: PointedList a -> PointedList a

-- | Move the focus to the previous element in the list. If the first
--   element is currently focused, loop to the last element.
previous :: PointedList a -> PointedList a

-- | An alias of <a>deleteRight</a>.
delete :: PointedList a -> Maybe (PointedList a)

-- | 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
--   <tt>Nothing</tt>.
deleteLeft :: PointedList a -> Maybe (PointedList a)

-- | 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 <tt>Nothing</tt>.
deleteRight :: PointedList a -> Maybe (PointedList a)