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RE: question about subtyping and type annotations

From: Michael Rys <mrys@microsoft.com>
Date: Fri, 24 Feb 2006 12:39:45 -0800
Message-ID: <07D2490E9E33124B8ED67F01E828B9E715E1FE@RED-MSG-70.redmond.corp.microsoft.com>
To: "Frans Englich" <frans.englich@telia.com>, <www-ql@w3.org>

The main negative impact will be that type inspection will result in
different results in typeswitch and instance of statements.

That is obviously not conductive to interoperable semantics.

Best regards
Michael

> -----Original Message-----
> From: www-ql-request@w3.org [mailto:www-ql-request@w3.org] On Behalf
Of
> Frans Englich
> Sent: Friday, February 24, 2006 10:16 AM
> To: www-ql@w3.org
> Subject: Re: question about subtyping and type annotations
> 
> 
> On Friday 24 February 2006 16:57, you wrote:
> > > Section 3.12.5 Constructor Functions seems to be pretty clear
> > > about it:
> >
> > That only says they are equivalent to casts. Are casts exempt from
the
> > general rule of substitutability, which says that any expression can
> return
> > a value whose dynamic type is a subtype of the required type?
> 
> Another question is what the negative impact, if any, is when
returning
> say
> xs:byte when xs:integer is the static type(apart from Per Bothner's
> confusion
> when investigating these corner cases).
> 
> 
> 		Frans
Received on Friday, 24 February 2006 20:39:54 UTC

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