datatype option a = None | Some of a
val none : option int = None
val some_1 : option int = Some 1
val f = fn t ::: Type => fn x : option t =>
case x of None => None | Some x => Some (Some x)
val none_again = f none
val some_1_again = f some_1
val show = fn t ::: Type => fn x : option t => case x of None => "None" | Some _ => "Some"
val page = fn x =>
{cdata (show x)}
val main : unit -> page = fn () =>
None
Some 1