table t : {A : int}
fun main () : transaction page =
let
fun check () =
r <- oneRow (SELECT SUM(t.A) AS X FROM t);
return (if r.X < 0 then
(Some 3, None)
else
(None, Some "Hi"))
fun show (t ::: Type) (_ : show t) (opt : option t) =
case opt of
None => None
| Some v => {[v]}
in
s <- source (None, None);
return