containers-0.2.0.0: Assorted concrete container types

Portabilityportable
Stabilityexperimental
Maintainerlibraries@haskell.org

Data.Sequence

Contents

Description

General purpose finite sequences. Apart from being finite and having strict operations, sequences also differ from lists in supporting a wider variety of operations efficiently.

An amortized running time is given for each operation, with n referring to the length of the sequence and i being the integral index used by some operations. These bounds hold even in a persistent (shared) setting.

The implementation uses 2-3 finger trees annotated with sizes, as described in section 4.2 of

Note: Many of these operations have the same names as similar operations on lists in the Prelude. The ambiguity may be resolved using either qualification or the hiding clause.

Synopsis

Documentation

data Seq a Source

General-purpose finite sequences.

Instances

Monad Seq 
Functor Seq 
Typeable1 Seq 
MonadPlus Seq 
Foldable Seq 
Traversable Seq 
Eq a => Eq (Seq a) 
Data a => Data (Seq a) 
Ord a => Ord (Seq a) 
Read a => Read (Seq a) 
Show a => Show (Seq a) 
Monoid (Seq a) 

Construction

empty :: Seq aSource

O(1). The empty sequence.

singleton :: a -> Seq aSource

O(1). A singleton sequence.

(<|) :: a -> Seq a -> Seq aSource

O(1). Add an element to the left end of a sequence. Mnemonic: a triangle with the single element at the pointy end.

(|>) :: Seq a -> a -> Seq aSource

O(1). Add an element to the right end of a sequence. Mnemonic: a triangle with the single element at the pointy end.

(><) :: Seq a -> Seq a -> Seq aSource

O(log(min(n1,n2))). Concatenate two sequences.

fromList :: [a] -> Seq aSource

O(n). Create a sequence from a finite list of elements. There is a function toList in the opposite direction for all instances of the Foldable class, including Seq.

Deconstruction

Additional functions for deconstructing sequences are available via the Foldable instance of Seq.

Queries

null :: Seq a -> BoolSource

O(1). Is this the empty sequence?

length :: Seq a -> IntSource

O(1). The number of elements in the sequence.

Views

data ViewL a Source

View of the left end of a sequence.

Constructors

EmptyL

empty sequence

a :< (Seq a)

leftmost element and the rest of the sequence

Instances

Functor ViewL 
Typeable1 ViewL 
Foldable ViewL 
Traversable ViewL 
Eq a => Eq (ViewL a) 
Data a => Data (ViewL a) 
Ord a => Ord (ViewL a) 
Read a => Read (ViewL a) 
Show a => Show (ViewL a) 

viewl :: Seq a -> ViewL aSource

O(1). Analyse the left end of a sequence.

data ViewR a Source

View of the right end of a sequence.

Constructors

EmptyR

empty sequence

(Seq a) :> a

the sequence minus the rightmost element, and the rightmost element

Instances

Functor ViewR 
Typeable1 ViewR 
Foldable ViewR 
Traversable ViewR 
Eq a => Eq (ViewR a) 
Data a => Data (ViewR a) 
Ord a => Ord (ViewR a) 
Read a => Read (ViewR a) 
Show a => Show (ViewR a) 

viewr :: Seq a -> ViewR aSource

O(1). Analyse the right end of a sequence.

Indexing

index :: Seq a -> Int -> aSource

O(log(min(i,n-i))). The element at the specified position, which should be a positive integer less than the size of the sequence. If the position is out of range, index fails with an error.

adjust :: (a -> a) -> Int -> Seq a -> Seq aSource

O(log(min(i,n-i))). Update the element at the specified position. If the position is out of range, the original sequence is returned.

update :: Int -> a -> Seq a -> Seq aSource

O(log(min(i,n-i))). Replace the element at the specified position. If the position is out of range, the original sequence is returned.

take :: Int -> Seq a -> Seq aSource

O(log(min(i,n-i))). The first i elements of a sequence. If i is negative, take i s yields the empty sequence. If the sequence contains fewer than i elements, the whole sequence is returned.

drop :: Int -> Seq a -> Seq aSource

O(log(min(i,n-i))). Elements of a sequence after the first i. If i is negative, take i s yields the whole sequence. If the sequence contains fewer than i elements, the empty sequence is returned.

splitAt :: Int -> Seq a -> (Seq a, Seq a)Source

O(log(min(i,n-i))). Split a sequence at a given position. splitAt i s = (take i s, drop i s).

Transformations

reverse :: Seq a -> Seq aSource

O(n). The reverse of a sequence.