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|
datatype t' = O | S of source t'
type t = source t'
val zero = source O
fun inc n =
v <- get n;
case v of
O =>
n' <- source O;
set n (S n')
| S n => inc n
fun dec n =
let
fun dec' last n =
v <- get n;
case v of
O => (case last of
None => return ()
| Some n' => set n' O)
| S n' => dec' (Some n) n'
in
dec' None n
end
fun render [ctx] [inp] [[Body] ~ ctx] (xml : xml ([Body] ++ ctx) inp []) n =
let
fun render n =
n <- signal n;
return (render' n)
and render' n =
case n of
O => <xml/>
| S n => <xml>
{xml}
<dyn signal={render n}/>
</xml>
in
<xml><dyn signal={render n}/></xml>
end
|
