Modulecontainers-0.7Haskell2010

Data.Containers.ListUtils

This module provides efficient containers-based functions on the list type.

In the documentation, n is the number of elements in the list while d is the number of distinct elements in the list. W is the number of bits in an Int.

4 values

Packagecontainers-0.7
Exports4
LanguageHaskell2010
LicenceBSD-3-Clause
SourceListUtils.hs

valuenubOrd :: Ord a => [a] -> [a]

O(n \log d) . The nubOrd function removes duplicate elements from a list. In particular, it keeps only the first occurrence of each element. By using a Set internally it has better asymptotics than the standard nub function.

Strictness

nubOrd is strict in the elements of the list.

Efficiency note

When applicable, it is almost always better to use nubInt or nubIntOn instead of this function, although it can be a little worse in certain pathological cases. For example, to nub a list of characters, use

 nubIntOn fromEnum xs

valuenubOrdOn :: Ord b => (a -> b) -> [a] -> [a]

The nubOrdOn function behaves just like nubOrd except it performs comparisons not on the original datatype, but a user-specified projection from that datatype.

Strictness

nubOrdOn is strict in the values of the function applied to the elements of the list.

valuenubInt :: [Int] -> [Int]

O(n \min(d,W)) . The nubInt function removes duplicate Int values from a list. In particular, it keeps only the first occurrence of each element. By using an IntSet internally, it attains better asymptotics than the standard nub function.

See also nubIntOn, a more widely applicable generalization.

Strictness

nubInt is strict in the elements of the list.

valuenubIntOn :: (a -> Int) -> [a] -> [a]

The nubIntOn function behaves just like nubInt except it performs comparisons not on the original datatype, but a user-specified projection from that datatype. For example, nubIntOn fromEnum can be used to nub characters and typical fixed-with numerical types efficiently.

Strictness

nubIntOn is strict in the values of the function applied to the elements of the list.