fun grupper 0 x = [x]
  | grupper n x =if length(x) > n then (List.take(x,n))::(grupper n (List.drop(x,n))) else [x];



fun removeelement (x::xs) y = if x = y then (removeelement xs y) else x::(removeelement xs y)
  | removeelement [] _ = []

fun klassdel2 k = map (fn x => [[x],(removeelement k x )]) k

fun klassdelsingels x = map (fn x => [x]) x;

fun klassdelmid (k as x::xs) y = let  val len = length k; in  if x <> y then   if len > 2 andalso len mod 2 = 0 then [(grupper 2 k)]@(klassdelmid (List.drop(k,1)@[x]) y )   else [[k]]   else []
	 end
  | klassdelmid [] _ = [];

fun klassdelpar x = let
val len = length x div 2;
val nyliste =List.drop(x,len)@List.take(x,len); in (klassdelmid x (List.last(x)))@(klassdelmid nyliste (List.last(nyliste)))
end


fun member(x,ys) = List.exists (fn y => x = y) ys;


(* offtrack
fun klassdel1 (k as x::xs)  n =
let
val len = length k;
val midlist = List.drop(k,n);
val endlist = List.drop(k,(len-n));
val nyliste =List.drop(x,len)@List.take(x,len);

in [(List.take(k,n)),(List.filter (fn x => not (member(x,endlist))) midlist),(endlist)] @(klassdel1 [nyliste n)

end
  | klassdel1 _ _ = [] )*)

fun klassdel1sub (k as x::xs) = let
val len = length k;
val midlist = List.drop(k,1);
val endlist = List.drop(k,(len-1));
val nyliste =List.drop(x,len)@List.take(x,len);
in if length k > 3 then [[x],(List.filter (fn x => not (member(x,endlist))) midlist),(endlist)]
else []
end

  | klassdel1sub _  = []


fun klassdel1 k = let
val mid = (length k) div 2;
val len = length k;
val nyliste =List.drop(k,len div 2)@List.take(k,len div 2 ); in
if length (k) > 4 then k else k
end


(* FUCKING LORTE KOMBANITORIK TO DO:

lav enderne, samt nyliste ender *)