Translate imperative control flow with break-s/continue-s to haskell

Posted by dorserg on Stack Overflow See other posts from Stack Overflow or by dorserg
Published on 2010-12-22T18:47:23Z Indexed on 2010/12/23 11:54 UTC
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Consider the following imperative code which finds the largest palindrome among products of 3-digit numbers (yes, it's the one of the first tasks from "Project of [outstanding mathematician of 18th century]" site):

curmax = 0
for i in range(999,100):
for j in range(999,100):
    if ((i*j) < curmax): break
    if (pal(i*j)):
        curmax = i*j
        break
print curmax

As I'm learning Haskell currently, my question is, how do you translate this (and basically any imperative construct that contains something more complex than just plain iteration, e.g. breaks, continues, temporary variables and all this) to Haskell?

My version is

maxpal i curmax
    | i < 100 = curmax
    | otherwise = maxpal (i-1) (innerloop 999)
    where 
        innerloop j
            | (j < 100) || (p < curmax) = curmax
            | pal p = p
            | otherwise = innerloop (j-1)
            where p = i*j
main = print $ maxpal 999 0

but this looks like we're still in imperative uglytown.

So what could you advise, what are the approaches of dealing with such cases FP-style?

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