https://www.colorless-sight.jp:443/wiki/?ProjectEular%2FProblem4
[[ProjectEular]] -- Problem 4 module Main (main) where main :: IO () main = print $ problem4 problem4 :: (Integral a) => a problem4 = maximum [ x * y | x <- [100..999], y <- [x..999], is_palindrome (x * y) ] is_palindrome :: (Integral a) => a -> Bool is_palindrome num = reverse (show num) == show num