[Ur] Documentation & codes

[Adam Chlipala]

Karn Kallio wrote:
>> if anyone's worried about Ur/Web surviving or gaining
>> wide-spread adoption, well, just fill in as much
>> info/examples on the Wiki as you can, and add any usable
>> code you might have, or link to your projects.
>>      
> Good idea!  Since I was quite confused about folders a couple of days ago (
> until Adam pointed out the problem .. thanks! ) I put a sample of usage of
> fold on the Wiki.
>
> http://www.impredicative.com/wiki/index.php/Using_Top.Fold_to_count_fields_of_a_record
>    

I've appended my own version of the code, which takes some convenient 
shortcuts.