sort -u for arbitrary haskell lists

DecorateSortUniq.hs

module DecorateSortUniq where

import Data.List

decorateSortUniq :: Ord a => [a] -> [a]
decorateSortUniq = map snd . sortBy (\(a,_) (b,_)->compare a b) . uniq snd . sortBy (\(_,a) (_,b)->compare a b) . zip [0..]
                   where uniq f (x:y:xs) = if f x == f y then uniq f (x:xs) else x:uniq f (y:xs)
                         uniq _ (x:_)    = [x]