[Bug 14840] New: [XDM 3.0] Function types in the type hierarchy diagram

http://www.w3.org/Bugs/Public/show_bug.cgi?id=14840

           Summary: [XDM 3.0] Function types in the type hierarchy diagram
           Product: XPath / XQuery / XSLT
           Version: Recommendation
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Data Model 3.0
        AssignedTo: ndw@nwalsh.com
        ReportedBy: mike@saxonica.com
         QAContact: public-qt-comments@w3.org


The type hierarchy diagram used in both XDM and F+O shows the type

function(item()*) as item()*

with four (example) subtypes, namely

function(item()*) as item()
function(item()*) as item()?
function(item()*) as item()+
function(item()) as item()

This is incorrect. (function(P) as Q) is a subtype of (function(R) as S) if R
is a subtype of P and Q is a subtype of S. Therefore the last of these four
illustrative subtypes is correct.

I'm not a graphical kind of person, so I will leave the correction of this to
someone else. I have always thought the whole diagram highly misleading. Even
its title is wrong, since our types form a lattice rather than a hierarchy. My
vote would be to remove it entirely.

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Received on Wednesday, 16 November 2011 11:29:00 UTC