Re: [xsl] Scope of variables

Subject: Re: [xsl] Scope of variables
From: David Carlisle <davidc@xxxxxxxxx>
Date: Fri, 9 May 2003 09:46:26 +0100
> [DAVID] What did you mean by this statement:
> The "variable value can't change" mantra refers to the fact that there
> is not an analogue of
> x=x+1
> wich some people, corrupted by procedural languages seem to feel
> is a natural thing to write, whereas it is obviously an affront to the
> laws of nature, unless x happens to be 0:-)
> David

The term variable comes from mathematics and if in mathematics you see
then one could deduce (by subtracting x from both sides) that
which is false, implying the original statement is false.

When I first was shown programming (Fortran at school in the mid 70's)
this aspect of fortran allowing variables to change their definition
was the main "strange" thing about programming languages that all the
books stressed. that programming languages had these strange imperative
features because they were designed to be easily executed by machines
rather than easily understood by humans.

A generation later and things have changed: machines are now more
powerful and so programming languages using more natural declarative
constructs are now feasible. Let the machine do the work and have the
language more suitable for humans. But things are not so simple, it
seems that in the intervening time humans have got used to the
imperative machine-oriented languages and are now unsettled by human
oriented declarative languages. You can't win....


This e-mail has been scanned for all viruses by Star Internet. The
service is powered by MessageLabs. For more information on a proactive
anti-virus service working around the clock, around the globe, visit:

 XSL-List info and archive:

Current Thread