Safe Haskell | None |
---|---|
Language | Haskell2010 |
This module defines a type for sorted lists, together with several functions to create and use values of that type. Many operations are optimized to take advantage of the list being sorted.
Synopsis
- data SortedList a
- toSortedList :: Ord a => [a] -> SortedList a
- fromSortedList :: SortedList a -> [a]
- singleton :: a -> SortedList a
- repeat :: a -> SortedList a
- replicate :: Int -> a -> SortedList a
- iterate :: Ord a => (a -> a) -> a -> SortedList a
- uncons :: SortedList a -> Maybe (a, SortedList a)
- insert :: Ord a => a -> SortedList a -> SortedList a
- delete :: Ord a => a -> SortedList a -> SortedList a
- deleteAll :: Ord a => a -> SortedList a -> SortedList a
- take :: Int -> SortedList a -> SortedList a
- drop :: Int -> SortedList a -> SortedList a
- splitAt :: Int -> SortedList a -> (SortedList a, SortedList a)
- takeWhile :: (a -> Bool) -> SortedList a -> SortedList a
- dropWhile :: (a -> Bool) -> SortedList a -> SortedList a
- span :: (a -> Bool) -> SortedList a -> (SortedList a, SortedList a)
- partition :: (a -> Bool) -> SortedList a -> (SortedList a, SortedList a)
- filter :: (a -> Bool) -> SortedList a -> SortedList a
- filterLT :: Ord a => a -> SortedList a -> SortedList a
- filterGT :: Ord a => a -> SortedList a -> SortedList a
- filterLE :: Ord a => a -> SortedList a -> SortedList a
- filterGE :: Ord a => a -> SortedList a -> SortedList a
- elemOrd :: Ord a => a -> SortedList a -> Bool
- findIndices :: (a -> Bool) -> SortedList a -> SortedList Int
- map :: Ord b => (a -> b) -> SortedList a -> SortedList b
- mapDec :: Ord b => (a -> b) -> SortedList a -> SortedList b
- unfoldr :: Ord a => (b -> Maybe (a, b)) -> b -> SortedList a
- reverse :: SortedList a -> SortedList (Down a)
- reverseDown :: SortedList (Down a) -> SortedList a
- nub :: Eq a => SortedList a -> SortedList a
- intersect :: Ord a => SortedList a -> SortedList a -> SortedList a
- union :: Ord a => SortedList a -> SortedList a -> SortedList a
Type
data SortedList a Source #
Type of sorted lists. Any (non-bottom) value of this type
is a sorted list. Use the Monoid
instance to merge sorted
lists.
Instances
List conversions
toSortedList :: Ord a => [a] -> SortedList a Source #
Create a SortedList
by sorting a regular list.
fromSortedList :: SortedList a -> [a] Source #
O(1). Create a list from a SortedList
. The returned list
is guaranteed to be sorted.
Construction
singleton :: a -> SortedList a Source #
O(1). Create a sorted list with only one element.
repeat :: a -> SortedList a Source #
An infinite list with all its elements equal to the given argument.
replicate :: Int -> a -> SortedList a Source #
Replicate a given number of times a single element.
iterate :: Ord a => (a -> a) -> a -> SortedList a Source #
Create a sorted list by repeatedly applying the same function to an element, until the image by that function is stricly less than its argument. In other words:
iterate f x = [x, f x, f (f x), ... ]
With the list ending whenever
f (f (... (f (f x)) ...)) < f (... (f (f x)) ...)
.
If this never happens, the list will be infinite.
By definition:
iterate f = unfoldr (\x -> Just (x, f x))
Deconstruction
uncons :: SortedList a -> Maybe (a, SortedList a) Source #
O(1). Decompose a sorted list into its minimal element and the rest.
If the list is empty, it returns Nothing
.
Inserting
insert :: Ord a => a -> SortedList a -> SortedList a Source #
O(n). Insert a new element in a sorted list.
Deleting
delete :: Ord a => a -> SortedList a -> SortedList a Source #
Delete the first occurrence of the given element.
deleteAll :: Ord a => a -> SortedList a -> SortedList a Source #
Delete all occurrences of the given element.
Sublists
take :: Int -> SortedList a -> SortedList a Source #
Extract the prefix with the given length from a sorted list.
drop :: Int -> SortedList a -> SortedList a Source #
Drop the given number of elements from a sorted list, starting from the smallest and following ascending order.
splitAt :: Int -> SortedList a -> (SortedList a, SortedList a) Source #
Split a sorted list in two sublists, with the first one having length equal to the given argument, except when the length of the list is less than that.
takeWhile :: (a -> Bool) -> SortedList a -> SortedList a Source #
Return the longest prefix of a sorted list of elements that satisfy the given condition.
dropWhile :: (a -> Bool) -> SortedList a -> SortedList a Source #
Return the suffix remaining after dropping the longest prefix of elements that satisfy the given condition.
span :: (a -> Bool) -> SortedList a -> (SortedList a, SortedList a) Source #
Return the longest prefix of a sorted list of elements that satisfy the given condition, and the rest of the list.
Filtering
partition :: (a -> Bool) -> SortedList a -> (SortedList a, SortedList a) Source #
O(n). Divide a sorted list into two lists, one with all the elements that satisfy the given predicate, and another list with the rest of elements.
filter :: (a -> Bool) -> SortedList a -> SortedList a Source #
O(n). Extract the elements of a list that satisfy the predicate.
filterLT :: Ord a => a -> SortedList a -> SortedList a Source #
O(n). Select only elements that are strictly less than the argument.
filterGT :: Ord a => a -> SortedList a -> SortedList a Source #
O(n). Select only elements that are strictly greater than the argument.
filterLE :: Ord a => a -> SortedList a -> SortedList a Source #
O(n). Select only elements less or equal to the argument.
filterGE :: Ord a => a -> SortedList a -> SortedList a Source #
O(n). Select only elements greater or equal to the argument.
Queries
findIndices :: (a -> Bool) -> SortedList a -> SortedList Int Source #
O(n). Return the indices of all elements in a sorted list that satisfy the given condition.
map
function
map :: Ord b => (a -> b) -> SortedList a -> SortedList b Source #
Map a function over all the elements of a sorted list.
Note that map
will hang if the argument is an infinite list.
Even though SortedList
can't be made an instance of Functor
,
map
does hold the Functor
laws (for finite lists).
We can't however write an instance because of the Ord
instance requirement on the type of
the elements of the result list. Therefore, while SortedList
is not a functor type in general, it is when restricted to elements of
orderable types (for finite lists).
The complexity range goes from O(n) (if the function is monotonically increasing)
to O(n²) (if the function is monotonically decreasing). These are the best
and worst case scenarios. We provide an alternative (mapDec
) where monotonically
decreasing functions are the best case scenario.
mapDec :: Ord b => (a -> b) -> SortedList a -> SortedList b Source #
Just like map
, but favoring functions that are monotonically decreasing instead
of those that are monotonically increasing.
Unfolding
unfoldr :: Ord a => (b -> Maybe (a, b)) -> b -> SortedList a Source #
Dual (sort of) to foldr
for sorted lists. It builds a sorted list from
a generator function and an initial element. The generator function is
applied to the initial element, and then it will produce either Nothing
- meaning that the list building must stop - or Just
applied to the
value that is going to be added to the list, and a new accumulator to be fed
to the generator function. The list building will stop prematurely if the
generator function happens to create an element for the list that is strictly
smaller than the previous value.
Others
reverse :: SortedList a -> SortedList (Down a) Source #
O(n). Reverse a sorted list. The result uses Down
, thus it is a sorted
list as well. The following equality holds for any sorted list xs
:
map Down xs = reverse xs
Only available from base
version 4.6.0.0.
reverseDown :: SortedList (Down a) -> SortedList a Source #
O(n). Reverse a sorted list with elements embedded in the Down
type.
Only available from base
version 4.6.0.0.
Set operations
nub :: Eq a => SortedList a -> SortedList a Source #
O(n). Remove duplicate elements from a sorted list.
intersect :: Ord a => SortedList a -> SortedList a -> SortedList a Source #
O(n+m). Intersection of sorted lists. If the first list contains duplicates, so will the result.
union :: Ord a => SortedList a -> SortedList a -> SortedList a Source #
Union of sorted lists. Duplicates, and elements of the first list, are removed from the the second list, but if the first list contains duplicates, so will the result.