5914 2008-07-30 12:10:30 +0000 [FS]: Normalization of treat as 2008-07-31 07:41:37 +0000 1 1 1 Unclassified XPath / XQuery / XSLT Formal Semantics 1.0 Recommendation PC Windows NT CLOSED INVALID P2 normal --- 1 tim jmdyck public-qt-comments oldest_to_newest 21389 0 tim 2008-07-30 12:10:30 +0000 In Bug 5672, it was clarified that treat as can be evaluated lazily. I'm fairly sure that the input of a typeswitch expression _can't_ be evaluated lazily, yet treat as is specified in FS to be normalized to a typeswitch expression: [Expr treat as SequenceType]Expr == typeswitch ([ Expr ]Expr) case $fs:new as SequenceType return $fs:new default $fs:new return fn:error() Is this normalization rule correct? With the function: declare function local:items() { (1, 2, 3, "four") }; consider: (local:items() treat as xs:integer*)[position() lt 4] and: (typeswitch ( local:items() ) case $new as xs:integer* return $new default return fn:error())[position() lt 4] 21403 1 jmdyck 2008-07-31 01:47:41 +0000 The dynamic semantics in the FS generally follows an 'eager' or 'strict' evaluation strategy. (E.g., for a function call, it evaluates all arguments before invoking the function.) The normalization rule for 'treat as' is just another example of that. 21406 2 tim 2008-07-31 07:41:16 +0000 OK - thanks. This (I think) is the only normalization rule that an implementation might want to avoid!