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Re: IfExpr has a mandatory else clause

From: Jonathan Robie <jonathan.robie@datadirect.com>
Date: Tue, 27 Jan 2004 08:02:53 -0500
Message-Id: <6.0.0.22.2.20040127080100.02c967e8@ncmail.datadirect-technologies.com>
To: "TAN Kuan Hui" <kuanhui@xemantics.com>, "Bas de Bakker" <bas@x-hive.com>, <www-ql@w3.org>

At 04:49 AM 1/26/2004, TAN Kuan Hui wrote:
>So is grammar ambiguity the reason that IfExpr has a
>mandatory else clause ?

Yes.

>Are there other design considerations ?

Not really.

Well, there is one justification that makes some sense. This is a 
functional language, every expression evaluates to something, and if the 
conditional expression evaluates to the empty sequence, there is some 
virtue to saying so explicitly. That's not much of a reason, but it will do 
as a post-hoc rationalization ;->

But resolving the ambiguity is important. For what it's worth, every entry 
in this thread is reminiscent of discussions we had at length within the 
Working Group. These are reasonable positions, but not new ones.

Jonathan  
Received on Tuesday, 27 January 2004 21:30:58 GMT

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