Folks more knowledgable than me, correct me if I'm wrong but $seq[n] is shorthand for $seq[posn() = n]
which is why something like (1 to 10)[xdmp:random(9) + 1] can yield counter-inituitive results. The above would imply that short-circuiting as described is therefore not consistent with required behavior. How about fn:head((1,xdmp:sleep(1))) to solve this though? The sleep doesn't show up when I profile. fn:head(((),2)) Yields expected results. fn:head new at 6.0 From: [email protected] [mailto:[email protected]] On Behalf Of Jakob Fix Sent: 11 April 2013 08:07 To: MarkLogic Developer Discussion Subject: Re: [MarkLogic Dev General] (foo(), bar())[1]: is bar() evaluated if foo() exists? Hi, I was kind of hoping that this might be an occasion to use xdmp:eager() but wrapping Michael's test case in it doesn't change the time spent at all. BTW, what's the use case for xdmp:eager(), the documentation is a bit "xdmp:lazy()" about it ;-) cheers, Jakob. On Wed, Apr 10, 2013 at 11:40 PM, Geert Josten <[email protected]<mailto:[email protected]>> wrote: Hi Tim, I think it is like it is, because MarkLogic will probably attempt to evaluate both functions in parallel, which makes short circuiting difficult. But I would think that the optimizer should be able to detect such (.., ..)[1] tricks very easily, and be able to prevent that. Perhaps file an RFE at support? Cheers from Vegas, Geert > -----Oorspronkelijk bericht----- > Van: > [email protected]<mailto:[email protected]> > [mailto:general-<mailto:general-> > [email protected]<mailto:[email protected]>] > Namens Tim Finney > Verzonden: donderdag 11 april 2013 5:42 > Aan: MarkLogic Developer Discussion > Onderwerp: Re: [MarkLogic Dev General] (foo(), bar())[1]: is bar() evaluated > if foo() exists? > > Hi Michael, > > Thanks for that succinct demonstration. > > It would be a Good Thing if we could use the [1] trick knowing that it > would shortcircuit. > > Best, > > Tim Finney > > On 04/11/2013 11:38 AM, Michael Blakeley wrote: > > Not in my 6.0-2.3 environment. > > > > declare function local:foo() { > > 1 > > }; > > > > declare function local:bar() { > > xdmp:sleep(1000), > > 2 > > }; > > > > (local:foo(), local:bar())[1], > > xdmp:elapsed-time() > > => > > 1 > > PT1.001195S > > > > The profiler shows the xdmp:sleep too. So I only use the [1] trick when I > don't care about performance. > > > > -- Mike > > > > On 10 Apr 2013, at 20:08 , Jason Hunter > > <[email protected]<mailto:[email protected]>> > wrote: > > > >> It shortcuts out like you want. > >> > >> Sent from my iPhone > >> > >> On Apr 10, 2013, at 7:53 PM, Tim Finney > >> <[email protected]<mailto:[email protected]>> wrote: > >> > >>> Hi All, > >>> > >>> (foo(), bar())[1] > >>> > >>> can be used instead of > >>> > >>> if (exists(foo())) then foo() else bar(). > >>> > >>> But does MarkLogic evaluate bar() if I use the (foo(), bar())[1] > >>> construct and foo() exists? I'm interested to know because bar() could > >>> take a long time to evaluate. > >>> > >>> Best, > >>> > >>> Tim Finney > >>> _______________________________________________ > >>> General mailing list > >>> [email protected]<mailto:[email protected]> > >>> http://developer.marklogic.com/mailman/listinfo/general > >> _______________________________________________ > >> General mailing list > >> [email protected]<mailto:[email protected]> > >> http://developer.marklogic.com/mailman/listinfo/general > >> > > _______________________________________________ > > General mailing list > > [email protected]<mailto:[email protected]> > > http://developer.marklogic.com/mailman/listinfo/general > > _______________________________________________ > General mailing list > [email protected]<mailto:[email protected]> > http://developer.marklogic.com/mailman/listinfo/general _______________________________________________ General mailing list [email protected]<mailto:[email protected]> http://developer.marklogic.com/mailman/listinfo/general
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