Hi Gunther, Thanks for your mail. After some research, I don’t see a quick way to statically infer the type in the function you mentioned, mostly because it’s called recursively (while statically inferring the type of the function, the return type of map2 function is requested, and it will be the type of the function signature, because the inferred type is not available yet…).
Personally, I would love to see the return types readded, not only because it speeds up BaseX, but also because I think it’s a general advantage of XQuery to have typed functions, and . Do you think there is any chance to revert the change? Did you hear sth. about the performance of MarkLogic – is the version without argument types comparable to BaseX in terms of execution time, or much faster? All the best, Christian > in a recent update of REx parser generator (v5.37), some type specifications > were removed from generated XQuery and XSLT functions. This affects > tail-recursive functions, and it was done because it turned out that > MarkLogic fails to optimize tail calls, presumably due to an explicit type > check caused by the type specification (see > http://markmail.org/message/gxi26da4crk2v5ge ). > > Now it was reported that this change causes performance problems with BaseX > (see https://twitter.com/apb1704/status/714219874441146368 ). > > I reproduced the problem as follows: > > - download the XQuery 3.1 grammar from > http://bottlecaps.de/rex/CR-xquery-31-20151217.ebnf > > - generate a parser from it on http://bottlecaps.de/rex/ using command > line options: > > -xquery -tree -main > > - run the generated parser, using this command line > > basex -binput={42} CR-xquery-31-20151217.xquery > > This works OK, but it takes about 80 seconds. Some analysis showed that the > time can be influenced by putting back the type specification to function > p:map2, i.e. declaring 'as xs:integer' as the result type: > > declare function p:map2($c as xs:integer, $lo as xs:integer, $hi as > xs:integer) as xs:integer > > This variant completes in less than 3 seconds. But even when declaring a > return type of > > as xs:integer? > > which might be the type that can be inferred statically, it completes fast. > > Is this possibly a problem with the optimizer? > > Which variant of generated code would be preferable for BaseX - typed or > untyped? > > Thanks, > Gunther
