Project Euler Problem 068

import Data.List
t :: [Integer]
t=[1..10]
anspre :: [[[Integer]]]
anspre = [[[a,b,c],[d,c,e],[f,e,g],[h,g,i],[j,i,b]] |
       a<-t,
       b<-delete a t,
       c<-t \\ [a,b],
       let l = a+b+c,
       d<-t \\ [a,b,c],
       e<-t \\ [a,b,c,d],
       d+c+e==l,
       f<-t \\ [a,b,c,d,e],
       g<-t \\ [a,b,c,d,e,f],
       f+e+g==l,
       h<-t \\ [a,b,c,d,e,f,g],
       i<-t \\ [a,b,c,d,e,f,g,h],
       h+g+i==l,
       j<-t \\ [a,b,c,d,e,f,g,h,i],
       j+i+b==l] --60個解
concatenate :: (Ord a, Show a) => [[a]] -> [Char]
concatenate lst = concatMap show $ concat $ take 5 $ dropWhile ((/= minhead).head) cyl where
  minhead = minimum $ map head lst
  cyl = cycle lst
ans1 :: [Char]
ans1 = maximum $ map concatenate anspre --ほんとは数値比較すべき
-- 6531031914842725
main :: IO ()
main = print ans1