On Fri, Nov 28, 2008 at 1:53 PM, Torsten Otto
Hi all,
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" findAnswer (x:xs) | (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.
I believe you are looking for unsafePerformIO ( http://haskell.org/ghc/docs/latest/html/libraries/base/System-IO-Unsafe.html...). I'm not sure if it will work properly for random number generation, however,due to optimization issues. Michael