[Haskell-beginners] Wrapping random
t-otto-news at gmx.de
Fri Nov 28 16:53:32 EST 2008
I teach a high school class in Computer Science. The current
programming goal is to implement chat-bots, and we're using Haskell of
course. Now one of my students had the seemingly easy idea of having
the bot answer with a random sentence if it doesn't have "good" answer.
Random in Haskell has its problems. I understand why you can't just
call a function as you would in Java. I'm not firm enough with monads
myself (and certainly don't want to go there in the class beyond I/O)
so I'm calling for help here: Is there a way to wrap the generation of
random numbers so that for the students it works like a function?
We have this working:
> import System.Random
> main =
> do randomNumber <- randomRIO (1::Int,2)
> print (randomAnswer randomNumber)
> randomAnswer r
> | (r == 1) = "Nope!"
> | (r == 2) = "Absolutely!"
> | otherwise = "Error!"
Now, how can we use it for something like this:
>findAnswer  = "h"
> | (z == "unknown") = findAnswer xs
> | otherwise = z
> where z = findWord x lexikon
where instead of getting "h" we'd like to call a function that would
give us one of the strings out of randomAnswer.
(findAnswer looks through a list [(keyword,response)].
I've looked at realworldhaskell and the wikibook among other sources,
but I can't manage to piece anything useful together. How do I manage
to get something of type IO to represent itself as a String?
Any help would be greatly appreciated.
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