Project Euler Problem 040

import Data.Char

list :: [Char]
list = concatMap show [1..]
dn :: Int -> Char
dn n = list !! (n-1)
ans1 :: Int
ans1 =product $ map (digitToInt. dn) [1,10,100,1000,10000,100000,1000000]
ans2 :: Int
ans2=product $ map (digitToInt.((concatMap show [1..])!!).(flip (-) 1)) [10^i|i<-[1..6]]
ans3 :: Int
ans3=product $ map (digitToInt.((concatMap show [1..])!!).(subtract 1)) [10^i|i<-[1..6]]
ans4 :: Int
ans4=foldr(*)1$ map(\x->digitToInt$ concat[show x|x<-[0..]]!!(10^x))[0..6]
ans5 :: Int
ans5=product $ map (digitToInt.((concatMap show [0..])!!)) [10^i|i<-[1..6]]
ans6 :: Int
ans6=product $ map (digitToInt.((concatMap show [0..])!!).(10^)) [1..6]

-- 210
main :: IO ()
main = print ans1