hashNub is:exact

hashNub :: Hashable a => [a] -> [a]
relude Relude.Nub
Like nub but runs in <math> time and requires Hashable. 
>>> hashNub [3, 3, 3, 2, 2, -1, 1]
[3,2,-1,1]
hashNub :: (Hashable a, Eq a) => [a] -> [a]
classy-prelude ClassyPrelude
same behavior as nub, but requires Hashable & Eq and is O(n log n) https://github.com/nh2/haskell-ordnub
hashNub :: (Witherable t, Eq a, Hashable a) => t a -> t a
witherable Witherable
Removes duplicate elements from a list, keeping only the first occurrence. This is usually faster than ordNub, especially for things that have a slow comparison (like String). 
>>> hashNub [3,2,1,3,2,1]
[3,2,1]
hashNub :: Hashable a => [a] -> [a]
universum Universum.Nub
Like nub but runs in O(n * log_16(n)) time and requires Hashable. 
>>> hashNub [3, 3, 3, 2, 2, -1, 1]
[3,2,-1,1]