Ur/Web: tests/rpcO.ur annotate

RPC returning an option

author	Adam Chlipala <adamc@hcoop.net>
date	Sun, 08 Mar 2009 13:41:55 -0400
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rev	line source
adamc@641	1 table t : {A : int}
adamc@641	2
adamc@641	3 fun main () : transaction page =
adamc@641	4 let
adamc@641	5 fun check () =
adamc@641	6 r <- oneRow (SELECT SUM(t.A) AS X FROM t);
adamc@641	7 return (if r.X < 0 then
adamc@641	8 (Some 3, None)
adamc@641	9 else
adamc@641	10 (None, Some "Hi"))
adamc@641	11
adamc@641	12 fun show (t ::: Type) (_ : show t) (opt : option t) =
adamc@641	13 case opt of
adamc@641	14 None => <xml>None</xml>
adamc@641	15 \| Some v => <xml>{[v]}</xml>
adamc@641	16 in
adamc@641	17 s <- source (None, None);
adamc@641	18 return <xml><body>
adamc@641	19 <button value="Get It On!"
adamc@641	20 onclick={r <- check ();
adamc@641	21 set s r}/><br/>
adamc@641	22 <br/>
adamc@641	23 Current: <dyn signal={p <- signal s; return <xml>{show p.1}, {show p.2}</xml>}/>
adamc@641	24 </body></xml>
adamc@641	25 end

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