why must one have something inside {} ?

[David Lee]

I'm not suggesting "{}" is a 'no-op' I'm suggesting it parses equivalent to
{()}
Maybe in the next week or two I'll study the BNF in more detail and make a
formal suggestion as per Liam's suggestion for XQuery 3.0

So far I haven't seen any reason why it would be either 
1) Ambiguous
2) Cause parser confusion
3) Cause reader confusion 
4) Cause 'unexpected' things to happen

So far all the cases I can think of it would either be beneficial, closer to
what a programmer would expect and easier on the eye and hand.
Things like  
	element {} {} 
would still be static errors just like
	element  {()} {()} 



----------------------------------------
David A. Lee
http://x-query.com/mailman/listinfo/talk
http://www.xmlsh.org

-----Original Message-----
From: http://x-query.com/mailman/listinfo/talk [mailto:http://x-query.com/mailman/listinfo/talk] On Behalf
Of Michael Sokolov
Sent: Saturday, December 03, 2011 5:53 PM
To: David Lee
Cc: http://x-query.com/mailman/listinfo/talk
Subject: Re:  why must one have something inside {} ?


How about

  element {} {}

  text {}

  attribute {} {}

should those be no-ops too?

I don't think so, because

element {} {"not empty"}

would be problematic

On 12/3/2011 2:41 PM, David Lee wrote:
> Yes exactly !
> Function bodies should be able to be empty too ... its so simple !
>
> declare function notimplementedyet() {};
>
>
>
> ----------------------------------------
> David A. Lee
> http://x-query.com/mailman/listinfo/talk
> http://www.xmlsh.org
>
>
> -----Original Message-----
> From: http://x-query.com/mailman/listinfo/talk [mailto:http://x-query.com/mailman/listinfo/talk] On Behalf
> Of Michael Dyck
> Sent: Saturday, December 03, 2011 2:28 PM
> To: http://x-query.com/mailman/listinfo/talk
> Subject: Re:  why must one have something inside {} ?
>
>
> David Lee wrote:
>> I am asking why in *XQuery*  the expression {} is not equivalent to {()}
> It might simply be that no-one suggested it.
>
>> Is there a case in *XQuery* where this would be problematic ?
> I don't think so.
>
> Probably the least-impact way for the spec to accomplish this would be
> to alter the syntax of EnclosedExpr, from
>       EnclosedExpr ::= "{" Expr "}"
> to
>       EnclosedExpr ::= "{" Expr? "}"
> and then say that, if the Expr is omitted, the EnclosedExpr yields the
> empty sequence. Note that, in addition to element and attribute content,
> this would also take effect when an EnclosedExpr is used as a function
> body, which may or may not be something you'd like as well.
>
> -Michael
>
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