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