:: Ord a => [a] -> [a] package:intro

O(n log n). The nubOrd function removes duplicate elements from a list. In particular, it keeps only the first occurrence of each element. Unlike the standard nub operator, this version requires an Ord instance and consequently runs asymptotically faster.
nubOrd "this is a test" == "this ae"
nubOrd (take 4 ("this" ++ undefined)) == "this"
\xs -> nubOrd xs == nub xs
The sort function implements a stable sorting algorithm. It is a special case of sortBy, which allows the programmer to supply their own comparison function. Elements are arranged from from lowest to highest, keeping duplicates in the order they appeared in the input.
>>> sort [1,6,4,3,2,5]