[Ur] Looking for a minimal example using source / signal - eg, User types into a textbox, changes appear below in an <xml> fragment

Fri Aug 14 16:09:18 EDT 2015

The subject of your message seems to be a clear description of a 
particular kind of example, which I will claim is already present in one 
of the main demos:
     http://www.impredicative.com/ur/demo/react.html

I think you've already found this one and the more complicated 
'increment' demo.  Maybe your question, then, has to do with the further 
complication that you introduce below.

On 08/13/2015 11:38 PM, Stefan Scott Alexander wrote:
> (3) Initial coding attempt:
>
> I thought I could just make some minor modifications, to change the 
> <cselect> in (1) to a <textbox>, as follows:
>
> fun main () =
>     s <- source "";
>     return <xml><body>
>       <textbox source={s} onchange={v <- get s; alert ("Now it's " ^ v)}>
> </textbox>
>
>       Hello, I'm <dyn signal={s <- signal s; return <xml>{[s]}</xml>}/>.
> </body></xml>
>
> However, this is giving lots of compile errors.

The problem here is just that you need <ctextbox> instead of <textbox>.  
The 'c' is for "client-side scripting."

> (4) Ultimately, what I want to develop is:
>
> (a) a <textbox> on the client, called `txbx`, which the user can 
> change by typing
>
> (b) a table `t` on the server, which will be "live-queryable" using 
> the <textbox>:
>
> (c) when user types something different in the <textbox>, there is an 
> <xml> fragment below the <textbox> which instantly changes:
>
> eg - the <xml> fragment might be something like this:
>
>   return queryX1 (SELECT Nam FROM t WHERE Nam LIKE '*' ^ {[txbx]} '*')
>                  (fn r => <xml>{[r.Nam]}<br/></xml>);
>
> I can't even get the simpler case (3) above to work. After I get (3) 
> to work, then I can try (4).

It's only possible to implement server-side interaction through RPCs.  
You probably want an event handler that blocks on an RPC result and then 
updates client-side sources appropriately when the results come in.
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