nub package:turtle

nub :: Ord a => Shell a -> Shell a
turtle Turtle.Prelude
Return a new Shell that discards duplicates from the input Shell: 
>>> view (nub (select [1, 1, 2, 3, 3, 4, 3]))
1
2
3
4
nubOn :: Ord b => (a -> b) -> Shell a -> Shell a
turtle Turtle.Prelude
Return a new Shell that discards duplicates determined via the given function from the input Shell: 
>>> view (nubOn id (select [1, 1, 2, 3, 3, 4, 3]))
1
2
3
4