1755 2005-07-19 20:55:16 +0000 [FS] technical: 7.2 Standard functions with specific typing rules 2005-09-06 13:15:14 +0000 1 1 1 Unclassified XPath / XQuery / XSLT Formal Semantics 1.0 Last Call drafts All All CLOSED FIXED P2 normal --- 1 jmdyck simeon public-qt-comments oldest_to_newest 4923 0 jmdyck 2005-07-19 20:55:16 +0000 7.2 Standard functions with specific typing rules It occurs to me that none of the inference rules in this section can be applied in the normal way. E.g., if you have a FunctionCall of the form fn:remove($a,$b) you can't just apply 7.2.11 (even though the FunctionCall matches the rule's conclusion), because 'fn' might be bound to a different namespace. Moreover, if you have FunctionCalls such as func:remove($a,$b) or remove($a,$b) then if 'func' is bound appropriately, or the default function namespace is set appropriately, you *do* want to apply 7.2.11, even though the calls do *not* match the rule's conclusion. This is a fair bit of fudging to impose on the inference process. One way to avoid the fudging would be to tweak each function to properly check the function name. E.g., change each rule of the (rough) form: statEnv |- Expr : Type ---------------------- statEnv |- fn:foo(Expr) : something(Type) to (something like): QName of func expands to (URI,NCName) URI = "http://www.w3.org/2005/04/xpath-functions" NCName = 'foo' statEnv |- Expr : Type ---------------------- statEnv |- QName(Expr) : something(Type) Then the normal inference process would cause the rule to match in exactly those cases that you want it to match. However, that would be a pain. Here's (what I think is) a much better solution. Currently, the rule-conclusions are judgments of the form statEnv |- QName (Expr1,...,Exprn) : Type and thus are (apparently) alternatives to 4.1.5 / STA / rule 1. Instead, make then judgments of the form statEnv |- expanded-QName(Type1,...,Typen) : Type (See Bug 1575.) So rather than being alternatives to 4.1.5 / STA / rule 1, they would be invoked *by* it, after it's already expanded QName (and typed the arguments). So now the rules would be alternatives to 4.1.5 / STA / rule (2|3). Roughly speaking, you would need to change each rule from: statEnv |- Expr : Type ---------------------- statEnv |- fn:foo(Expr) : something(Type) to: URI = "http://www.w3.org/2005/04/xpath-functions" NCName = 'foo' ---------------------- statEnv |- (URI,NCName)(Type) : something(Type) or, with suitably-defined shorthand, to just: ---------------------- statEnv |- (FN-URI,'foo')(Type) : something(Type) (which is even more concise than the current, since it doesn't need premises to get the types of the arguments). I think this would work fine for all the functions in 7.2 except for fn:collection and fn:doc, whose STA depends on the *form* of the argument, not just its type. For those two, I suppose you could use the first solution I suggested. 4948 1 jmdyck 2005-07-19 23:25:14 +0000 (In reply to comment #0) > > I think this would work fine for all the functions in 7.2 except for > fn:collection and fn:doc, whose STA depends on the *form* of the argument, > not just its type. Oh, and fn:subsequence. 5253 2 simeon 2005-07-27 15:22:45 +0000 I agree with the second proposed fix, beginning "However, that would be a pain. Here's (what I think is) a much better solution. Currently, the rule-conclusions are judgments of the form..." 5612 3 simeon 2005-08-31 15:32:03 +0000 The XML Query and XSLT WGs have accepted the bug, with the second proposed fix. - Jerome