fun isBeppo (s : string) : transaction string =
case s of
"Beppo" => return "Yup, that's him!"
| "Mephisto" => error Great googely moogely!
| _ => return "Who's that?"
fun listOf (n : int) =
if n < 0 then
error Negative!
else if n = 0 then
return []
else
ls <- listOf (n - 1);
return (n :: ls)
fun length ls =
case ls of
[] => 0
| _ :: ls' => 1 + length ls'
fun main () : transaction page =
s <- source "";
ns <- source "";
return