[Ur] Type signature for a form handler

Fri Oct 3 23:54:51 EDT 2014

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

(* The answer to the your question is :
   val login : { Username : string , Password : string } ->
transaction page
   The module gives a sample implementation and
   signature.

   Besides their usage in forms they I records helpful
   when defining a function with multiple arguments for
   example:

   and post' (title : string)
             (body : string)
             (username : string)
             (created : time) : xbody = ...

   would be:
   post' ( p : { Title : string
               , Body : string
               , Username : string
               , Create : time }) : xbody = ...

   So for function calls with many arguments I know what each
   parameter is being used for.

   e.g.
   (fn row => post' { Title = "tofu is so great"
                    , Body = <xml>...</xml>
                    , Username = row.Users.Username
                    , Create = row.Posts.Created})

   It is a trivial example but you can imagine more elaborate
   scenarios.

   I digress, hopeful my meandering is of some help and I have
   answered your question.  Below is sample implementation.

   Happy hacking
*)

signature AUTH = sig
    val login : { Username : string , Password : string } ->
transaction page
end
structure Auth : AUTH = struct
    fun login (r : { Username : string , Password : string }) :
transaction page =
    return
         <xml>
           <head><title>welcome to tofu palace</title></head>
           <body>
             <p>Username:{[r.Username]}</p>
             <p>Password:{[r.Password]}</p>
           </body>
         </xml>
end

fun login_form () : transaction page =
     return
         <xml>
           <head><title>welcome to tofu palace</title></head>
           <body>
             <form>
               Username:<textbox{#Username}/>
               Password:<password{#Password}/>
               <submit value="Login" action={Auth.login}/>
             </form>
           </body>
         </xml>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
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=uRh+
-----END PGP SIGNATURE-----