nub :: (Eq a) => [a] -> [a]
nub lista = nub_rec lista []
    where
        nub_rec :: (Eq a) => [a] -> [a] -> [a]
        nub_rec [] acc = acc
        nub_rec (x:xs) acc = nub_rec (filter (y -> if y == x then False else True) xs) (x:acc)

myNub :: Eq a => [a] -> [a]
myNub (x:xs) = x : filter (/= x) (myNub xs)
myNub [] = []

myNoop :: [a] -> [a]
myNoop l = foldr ( x xs -> x : xs) [] l

removeDuplicates :: Eq a => [a] -> [a]
removeDuplicates = foldr (z ys -> z : filter (/= z) ys) []