[Ur] Hamlet like XML, structured by indentation with tag autoclosing

[Adam Chlipala]

Here's how I'd write that example in Ur/Web.  I don't see an obvious 
difference in pleasantness vs. the Hamlet style.

fun mymodule (items : list string) : xbody = <xml>
   <h3>title</h3>
   <div>
     {case items of
          [] => <xml><p>Sorry, no items left</p></xml>
        | _ => <xml><ul>{List.mapX (fn item => 
<xml><li><b>{[item]}</b></li></xml>) items}</ul></xml>}
   </div>
</xml>


On 06/18/2015 09:54 AM, Gabriel Riba wrote:
> Correction:
>
> his indented xml has been designed as a template system for the yesod 
> web framework (http://www.yesodweb.com/).
>
> Lets make a comparison with equivalent code:
>
> (* --- hamlet style template *)
>
> fun mymodule items = <ixml>
>    <h3> title
>    <div>
>       $if {null items}
>          <p> Sorry, no items left
>       $else
>          <ul>
>             $forall {item} <- {items}
>                <li> <b>{[item]}</b>
> </ixml>
>
> (* ---------- without hamlet ---- *)
>
> val emptyListSnippet = <xml>
>                         <p> Sorry, no items left</p>
>                        </xml>
>
> fun listItemSnippet item = <xml>
>                       <li> <b>{[item]}</b> </li>
>                     </xml>
>
> fun listSnippet items =
>    List.foldr join <xml/> <|
>         List.map listItemSnippet items
>
> fun mymodule items =
> <xml>
>    <h3>title</h3>
>    <div>   { if null
>                   then emptyListSnippet
>                   else <xml>
>                           <ul>
>                               {listSnippet items}
>                           </ul>
>                        </xml>
>            }
>     </div>
> </xml>