filterLessTenA :: (Ord a, Num a) => [a] -> [a]
filterLessTenA xs = filter (< 10) xs

filterLessTenB :: (Ord a, Num a) => [a] -> [a]
filterLessTenB [] = []
filterLessTenB (x:xs)
    | x < 10    = x : filterLessTenB xs
    | otherwise = filterLessTenB xs