All of these are the same:

    [ (x,y) | x <- [1..5], y <- "abcd" ]


    do x <- [1..5]
       y <- "abcd"
       return (x,y)


    do { x <- [1..5] ; y <- "abcd"; return (x,y) }


    [1..5] >>= \x -> "abcd" >>= \y -> return (x,y)


    concatMap (\x -> concatMap (\y -> [(x,y)]) "abcd") [1..5]


    concat (map (\x -> concat (map (\y -> [(x,y)]) "abcd")) [1..5])



    
    
    concat (map 
                (\x-> concat (map 
                                  (\y -> [(x,y)]) 
                                                  "abcd")) [1..5])