Declaratieve Talen/Oplossing haskell nqueens

Mogelijke oplossing

nqueens::Int->[Int]
-------------------
nqueens n = let
				list = [1..n]
				permlist = perms list
			in
				getoklist permlist


getoklist::[[Int]]->[Int]
------------------------
getoklist [] = error "geen oplossing"
getoklist (x:xs) | listok x = x
				 | otherwise = getoklist xs


listok::[Int]->Bool
-------------------
listok [] = True
listok (a:as) = if (listok2 a as 1) == False then False
				else listok as
				
listok2::Int->[Int]->Int->Bool
------------------------------
listok2 _ [] _ = True
listok2 a (b:bs) kol | a == (b+kol) = False
					 | a == (b-kol) = False
					 | otherwise =  listok2 a bs (kol+1)
					 
					 
					 
--Permuteer de lijst
perms :: [k] -> [[k]]
---------------------
perms [] = [[]]
perms (x:xs) = concat (map (tussen x) (perms xs)) where 
            tussen e [] = [[e]]
            tussen e (y:ys) = (e:y:ys) : map (y:) (tussen e ys)