(* removes Ingredients from r1 recipe option list and returns recipe list *)
fun removeHelper names r1 =
    let
        val removed = List.map (fn e => remove names e) r1
        val onlySome = List.filter (fn e => isSome(e)) removed
    in
        List.map (fn e => valOf(e)) onlySome
    end

and remove names r =
    case r of
        Ingredient(s) => if List.foldl (fn(name, a) => name=s orelse a) false names then NONE else SOME(Ingredient(s))
        | AnyOf(r1) =>  let
                            val removed = removeHelper names r1
                        in
                            if List.length removed > 1 then SOME(AnyOf(removed))
                            else if List.length removed = 1 then SOME(List.nth(removed, 0))
                            else NONE
                        end
        | Action(s, r1) => let val removed = removeHelper names r1 in if List.length removed > 1 then SOME(Action(s, removed)) else NONE end