Re: [Exist-open] [SPAM] Re: Question re:syntax of higher order functions

[Efraim F. <efr...@gm...>]

Hi,

On 04/24/2012 10:56 AM, Gunther Rademacher wrote:
> Efraim Feinstein wrote
>> It looks like there is then no way to uniquely specify "zero or
>> one functions returning exactly one item."
>>
> That's what a ParenthesizedItemType is for:
>
>       (function() as item())?
>
> Also note that the 3.0 spec has an "extra-grammatical constraint" on
> occurrence indicators covering this:
>
> http://www.w3.org/TR/xquery-30/#parse-note-occurrence-indicators
>

Thanks! That would seem to solve the problem from the spec's 
perspective. As far as I can tell, the syntax is not supported in eXist 
(as of 2.0 preview r16247).

(Example test code:

xquery version "3.0";

declare function local:f($a as (function() as xs:string)?) {
  if (exists($a))
  then $a()
  else "b"
};

local:f(())

)

-- 
---
Efraim Feinstein
Lead Developer
Open Siddur Project
http://opensiddur.net
http://wiki.jewishliturgy.org