Hi all,

What's the best way to implement the following Python code in Haskell?
It is purposefully written in a functional style (and as a result will
kill your recursion stack every other run).

Here's my solution, using MonadRandom (from Hackage). There may be more infinite-listy ways of doing it, but I wasn't able to make it come out clean.

import Control.Monad.Random

many n = sequence . replicate n

untilM p m = do
x <- m
if p x then return x else untilM p m

getList :: MonadRandom m => m [Int]
getList = many 10 $ getRandomR (0,9)

main = print =<< evalRandIO (untilM (all even) getList)

# begin Python
from random import *

def genList ():
return [randint(0,9) for x in range(10)]

def randWhile (predicate):
result = genList ()
if predicate(result):
return result
else:
return randWhile (predicate)

def allEven (list):
return reduce(lambda x,y: x and y, [x%2 == 0 for x in list])

print randWhile (allEven)
# End Python

Thanks!
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