Project Euler Problem 006

import Control.Applicative
import Control.Monad
sq :: Integer -> Integer
sq = join (*)
s :: [Integer] -> Integer
s n = sq (sum n) - sum (map sq n)
m :: Integer
m = s [1..100]
--25164150
main :: IO ()
main = print m

-- 別解
l :: [Integer]
l = [1..100]
m2 :: Integer
m2 = (sum l)^2 - sum (map (^2) l)