[acjohnson55]

It's basically the same thing, except with that syntax, you have to label all the intermediate results

[bbcbasic]

To avoid labeling:

    routine :: Int -> Maybe Int  
    routine n = Just n >>= (divisorFilter 3) >>= (divisorFilter 2) >>= (divisorFilter 5)

    -- Supporting function
    divisorFilter :: Int -> Int -> Maybe Int
    divisorFilter d n
        | n `mod` d == 0 = Just n
        | otherwise = Nothing
        
    -- Using do syntax
    routine' :: Int -> Maybe Int  
    routine' n = do  
        first <- divisorFilter 3 n
        second <- divisorFilter 2 first
        divisorFilter 5 second