filterLess10Builtin :: [Double] -> [Double]
filterLess10Builtin xs = filter (< 10) xs

filterLess10Recursive :: [Double] -> [Double]
filterLess10Recursive [] = []
filterLess10Recursive (x:xs)
    | x < 10    = x : filterLess10Recursive xs
    | otherwise = filterLess10Recursive xs