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

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
O(n log n). The nubSort function sorts and removes duplicate elements from a list. In particular, it keeps only the first occurrence of each element.
nubSort "this is a test" == " aehist"
\xs -> nubSort xs == nub (sort xs)
Equivalent to drop 1, but likely to be faster and a single lexeme.
drop1 ""         == ""
drop1 "test"     == "est"
\xs -> drop 1 xs == drop1 xs