datatype t = datatype Basis.option

fun eq [a] (_ : eq a) =
    mkEq (fn x y =>
             case (x, y) of
                 (None, None) => True
               | (Some x, Some y) => x = y
               | _ => False)

fun ord [a] (_ : ord a) =
    mkOrd {Lt = fn x y =>
                   case (x, y) of
                       (None, Some _) => True
                     | (Some x, Some y) => x < y
                     | _ => False,
           Le = fn x y =>
                   case (x, y) of
                       (None, _) => True
                     | (Some x, Some y) => x <= y
                     | _ => False}

fun isNone [a] x =
    case x of
        None => True
      | Some _ => False

fun isSome [a] x =
    case x of
        None => False
      | Some _ => True

fun mp [a] [b] f x =
    case x of
        None => None
      | Some y => Some (f y)

fun bind [a] [b] f x =
    case x of
        None => None
      | Some y => f y