- From: <bugzilla@wiggum.w3.org>
- Date: Tue, 30 Oct 2007 04:31:16 +0000
- To: public-qt-comments@w3.org
- CC:

http://www.w3.org/Bugs/Public/show_bug.cgi?id=4841 ------- Comment #10 from jmdyck@ibiblio.org 2007-10-30 04:31 ------- At meeting 337, I was directed to propose a solution that did not change the results of static type analysis. This excludes all of the above suggestions except #2 in Comment #5. Here is a more fleshed-out version of that solution. (A) At every occurrence of "fn:subsequence" in 4.2.1 and 4.3.2: -- Change "fn:subsequence" to "fs:item-at". -- Delete the third argument (always "1"). (B) Create a new section: 7.1.13 The fs:item-at function fs:item-at($sourceSeq as item()*, $loc as xs:double) as item()? The fs:item-at function returns the item at a specified position in a sequence. Dynamic Evaluation If $loc is numeric-equal to the position of some item in $sourceSeq, that item is returned. (This implies that $sourceSeq is non-empty, and $loc is numeric-equal to an integer between 1 and n inclusive, where n is the number of items in $sourceSeq.) Otherwise, the empty sequence is returned. The function is roughly equivalent to the following user-defined function. declare function fs:item-at( $sourceSeq as item()*, $loc as xs:double) as item()? { if ($loc div 1 eq 0) then fn:subsequence($sourceSeq,$loc,1) else () }; Static Type Analysis The static typing rules for invocations of fn:item-at depend on the syntactic form of the second argument. By construction, this must be either $fs:last, $fs:position, or a NumericLiteral. Thus, those are the only cases considered by the following rules. [Then, from 7.2.13 / STA, move all but the last rule (and its preceding prose) to here, with the following changes: 'fn:subsequence' --> 'fs:item-at' (FN-URI,"subsequence") --> '(FS-URI,"item-at")' In each rule's conclusion, drop the function call's third arg (always "1"). ] (C) In "7.2.13 The fn:subsequence function": Introduction: Drop it. Static Type Analysis: Everything except the last rule (the catch-all case) has been moved to 7.1.13. Change the last rule's preceding prose to: The static type for the fn:subsequence is computed using prime and quantifier, which are defined in [8.4 Judgments for FLWOR and other expressions on sequences]. (D) In "C.1 Functions and Operators used in the Formal Semantics", drop the list item for fn:subsequence.

Received on Tuesday, 30 October 2007 04:31:25 UTC