[Ur] Set / Update values within a structure

Thu Nov 9 22:42:22 EST 2017

Hello all,

I am trying to use a structure but, I am stuck at one point. This is my
structure definition -

*functor Make(M : sig*
*                 val callback : _*
*             end) = struct*
*    val cb  = M.callback*

*    fun simple nn =*
*        cb(nn);*
*        return nn*
*end*

What I am trying to do is to initiate a structure with a callback function.
Below demonstrates using a function debugMe as a callback. This works
totally fine.

*fun debugMe a =*
*        alert a*

*structure AB = Mymaths.Make(struct*
*                               val callback = debugMe*
*                           end)*

*fun main()=*
*let*
*    fun callMe () =*
*        x <- AB.simple "test";*
*        debug x*

*in*
*    return <xml>*
*        <body>*
*            <h1> Sample </h1>*
*            <button value="Click Me" onclick={fn _ => callMe()}></button>*
*        </body>*
*        </xml>*
*end*

What I ultimately want to achieve is to be able to change the callback
function *debugMe* at a later point of time. Is it possible to set or
update values within a structure at a later point of time?

I am new to urweb and SML in general so pardon me if this is really silly.
Any help would be really appreciated. Thanks a lot!

Regards,
Harshita
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