3669 2006-09-07 15:46:07 +0000 Type checking of () GeneralOp [value] 2006-10-19 19:48:30 +0000 1 1 1 Unclassified XPath / XQuery / XSLT Formal Semantics 1.0 Candidate Recommendation PC Windows XP CLOSED INVALID P2 normal --- 1 tim simeon public-qt-comments oldest_to_newest 11492 0 tim 2006-09-07 15:46:07 +0000 The formal semantics expansion of: () eq 1 is some $v1 in fn:data(()) satisfies some $v2 in fn:data(1) satisfies let $u1 := fs:convert-operand($v1, $v2) return let $u2 := fs:convert-operand($v2, $v1) return fs:eq ($u1, $u2) Because: statEnv |- data on empty : empty fn:data(()) is of type empty. Therefore $u1 must be of type empty. This is bad news for convert-operand, since $expected is of type xs:anyAtomicType. 12039 1 simeon 2006-09-26 14:31:12 +0000 Tim, Since the title of your comment is on General comparisons, I believe you meant to say '() = 1' ? I am not sure I understand what the problem you are trying to point out is. The normalization should be indeed what you suggest: some $v1 in fn:data(()) satisfies some $v2 in fn:data(1) satisfies let $u1 := fs:convert-operand($v1, $v2) return let $u2 := fs:convert-operand($v2, $v1) return fs:eq ($u1, $u2) The inference should go as follows: () has type empty fn:data(()) has type empty the some expression is typed through a prime type. so $v1 will be of type 'none' which should make sure the rest of the type checking succeeds. This is because in fact 'some' does not iterate at all over the empty sequence, the rest of the expression will not even be evaluated. the final type for the expression should be xs:boolean. - Jerome 12046 2 tim 2006-09-26 15:07:34 +0000 > Since the title of your comment is on General comparisons, I believe you meant > to say '() = 1' ? Yes, my mistake. In another posting you made the point that, effectively, type empty is equivalent to none?, and also that none is a subtype of all other types. At the time of posting, I'd missed out the rule that prime(empty) = none. I had prime(empty) = empty, which was the root cause of my typechecking problem. Therefore this report can be ignored. Thanks for your help. 12053 3 simeon 2006-09-26 15:58:01 +0000 Sorry reopened this bug by mistake ^_^. Thanks for your quick response on this. - Jerome