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Re: [xsl] things about grouping


Subject: Re: [xsl] things about grouping
From: Ihe Onwuka <ihe.onwuka@xxxxxxxxx>
Date: Wed, 28 Nov 2012 11:47:27 +0000

Going to congregate my answers again.

On Wed, Nov 28, 2012 at 10:49 AM, Geert Bormans
<geert@xxxxxxxxxxxxxxxxxxx> wrote:
> Basically you are expecting that the semantics of a spoken language is
> copied 1 to 1 to the syntax of a programming language,

Thats a strawman.

> implying that the context should be found where you as a person (with your
> personal language and cultural background) would expect to find it.

Said cultural background being (in my case) week 1 of year 1  of
secondary school mathematics. I remember it clearly - Chapter 1 of my
Modern Mathematics textbook - Set Theory.

> That is dangerous, and from the programing language design not robust
> enough.
> I think you are overlooking the fact that for a machine you simply need to
> be more precise.
>
> Where do you draw the line?

I should ask you the opposite question.  If you advocate that  a
programming language implements constructs that have  a precise
mathematical meaning without  respecting the syntax AND the semantics
of  said mathematical construct, where do you draw the line?

Because basically thats what you're saying. That programming languages
can via specification construct their own reality and don't need to
respect the syntax and semantics of the domains whose concepts they
are implementing or modelling.


On Wed, Nov 28, 2012 at 10:41 AM, Andrew Welch <andrew.j.welch@xxxxxxxxx> wrote:
>
> One way to think about this is to visualise the tree of nodes in your
> head - visualise the whole input tree.   Then visualise the nodes
> selected by the LHS glowing one colour, and the nodes selected by the
> RHS glowing in a different colour.  It should then be easier to
> visualize those nodes selected by the LHS except those nodes also
> selected by the RHS, and also help with seeing the RHS selection being
> independent of the LHS.

Alternatively call the thing difference which is what it is and then
it's so much simpler to visualize with the prop we were given in
secondary school - Venn Diagrams.


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