exception NotEnaughOp of code;;
raise (NotEnaughOp s)

type code = Elem of bool | Not | And | Or | Xor;;

let eval listOfOper =

	let getVal l x =
		if  x = Not then not (List.hd l)
		else if (List.tl l = []) then raise (NotEnaughOp x)
		else (
			match x with
			| And ->  (List.hd l) && (List.hd (List.tl l))
			| Or ->  (List.hd l) || (List.hd (List.tl l))
			| Xor -> ((List.hd l) && not (List.hd (List.tl l))) || (not (List.hd l) && (List.hd (List.tl l)))
		)
	in

	let rec evalH (listOfOper, acc, currVal) =
		match listOfOper with
		[] -> List.hd acc
		| (x :: xs) -> if x = Elem true then evalH(xs, true :: acc, true)
			       else if x = Elem false then evalH(xs, false :: acc, false)

			       else evalH(xs, [(getVal acc x)], (getVal acc x))
	in

evalH (listOfOper, [], false) ;;