復習

f0 = concatMap (\a -> concatMap (\b -> concatMap (\c -> [a,b,c]) [5,6])[3,4])[1,2]

f1 = [1,2] >>= \a -> ([3,4] >>= \b -> ([5,6] >>= \c -> [a,b,c]))

f2 = do a <- [1,2]
        b <- [3,4]
        c <- [5,6]
        [a,b,c]

で
*Main> f0
[1,3,5,1,3,6,1,4,5,1,4,6,2,3,5,2,3,6,2,4,5,2,4,6]
*Main> f1
[1,3,5,1,3,6,1,4,5,1,4,6,2,3,5,2,3,6,2,4,5,2,4,6]
*Main> f2
[1,3,5,1,3,6,1,4,5,1,4,6,2,3,5,2,3,6,2,4,5,2,4,6]
*Main> 

あー、ぱっとはかけない。
なれなのかなぁ。なれるのかなぁ。