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. Regards, Torsten Otto
Hi Torsten,
An option would be to use "randoms" to generate an infinite list of
random numbers before hand and pass these numbers to your functions.
Of course that will mean you have to keep track of what numbers you
have used.
Control.Monad.Random would take care of this stuff for you however it
requires a simple understanding of monads.
Best of luck,
Steven
2008/11/29 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.
Regards, Torsten Otto _______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners
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
Torsten Otto wrote:
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!"
could be more concisely
randomAnswer r = ["Nope!", "Absolutely!"] !! r and 0-based rather than 1-based: main = do randomNumber <- randomRIO (0::Int,1) print (randomAnswer randomNumber)
for example, although it worked fine as-is, and it's possible to abstract more nicely than what I showed here too -Isaac
On Fri, Nov 28, 2008 at 10:53:32PM +0100, Torsten Otto wrote:
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.
Perhaps instead of using a random number, you could simulate randomness with some other technique. For example, if there is no good response in a particular situation, you could hash the input and map it to some predetermined responses. This would keep you in the IO monad (I think. I'm a total rookie at this). You could then useit as a vehicle to teach some other stuff such as the meaning of random in a computer environment (vs true randomness) and concepts of hashing (even looking into collisions in a simple way because the students will see that different situations reliably give rise to the same outout). .02 A
Thanks a bunch for the replies, they were much appreciated. In the meantime we talked in more depth than I had initially planned to about randomness, statefulness and even monads to some extent. (And the chatbot gives its random replies as was planned :-) ) Kind regards, Torsten
participants (5)
-
Andrew Sackville-West -
Isaac Dupree -
Michael Snoyman -
Steven Ashley -
Torsten Otto