[Ur] howto serve arbitrary files (PDF/ icons), and more

[Adam Chlipala]

Marc Weber wrote:
> 1)
> Which is the ur way to serve arbitrary files such as content-type
> application/pdf ?
>    

That would be the function [Basis.returnBlob].

>    Eg adding "allow url css/*" to the configuration file a link to
>    css/css.css complied. Status is still 404 (not found)
>
>    I also tried adding path css=./css
>    strace showed that urweb didn't even try to load a css.css file.
>    

Ur/Web executables contain no default web server functionality for 
reading from static files.  I recommend hosting static content with a 
traditional web server, possibly one that proxies to your application 
(via HTTP or FastCGI) for the dynamic content.

> 2)
> Does urweb support the system() FFI command? If not is there a small
> example which could help getting started with exploring FFI?
>
> system could be used for many quick&  dirty implementations.
>    

Dirty indeed. ;)  Ur/Web is designed to be completely transactional, 
where any action taken can be rolled back.  A general 'system' function 
obviously can't satisfy this property.

If you're willing to take your chances with non-undoable commands being 
run multiple times as your page handler restarts for various reasons, 
you might want to start from this example:
     http://www.impredicative.com/wiki/index.php/Ur_C_FFI_Example

> 3)
> How to specify the "index" file which will be used if no path is given?
>    

No such functionality in Ur/Web.  I again recommend using a traditional 
web server or proxy for this.