Hi. For learning, I was doing the "phone words" problem, where a function translates the digits of a phone number into all possible words. I am trying to connect this idea to the idea of list comprehensions / list monads (sort of the same thing, yes?) I know it is easy to do this: w = do two <- "ABC" three <- "DEF" four <- "GHI" -- and the other digits [[two, three, two, four]] -- for example But what if you don't know in advance what the digits will be? I'm not sure how to insert that deterministic component into this idea. So far, I have a framework like so: p dx = do undefined where m = map (\d -> case d of 2 -> "ABC" 3 -> "DEF" 4 -> "GHI" 5 -> "JKL" 6 -> "MNO" 7 -> "PRS" 8 -> "TUV" 9 -> "WXY" otherwise -> show d) dx I would appreciate any guidance.