Subject: [xsl] Re: Reference to variable cannot be resolved. From: "Dimitre Novatchev" <dnovatchev@xxxxxxxxx> Date: Fri, 14 Feb 2003 20:25:35 +0100 |
"David Carlisle" <davidc@xxxxxxxxx> wrote in message news:200302141743.RAA02084@xxxxxxxxxxxxxxxxxxxx > > > I am sure that if you were designing your own language you'd never > > allow such a practice. > > I think actually it's more normal to allow this than not. > in lisp dialects it's not usually an error if a let binding shadows > a binding of the same name. in lambda calculus you allow > lambda x. ( x .... lambda x. (....x ) ... x) > with the usual understanding that the 1st and 3rd x are a different > variable (bound by the outer lambda) to the 2nd x which is bound by the > inner lamda. This is not exactly the same. The leftmost x has the greatest scope, which covers the scope of the inner x. This is really shadowing. What the WD specifies is two or more x-s with exactly the same scope. This is confusing, to say the least. Also, the WD is lacking the Lisp dialects brackets, therefore guessing what the real scope of one of the many identically named variables is -- this may become a rather difficult and unpleasant task. I think the biggest problem here is that the scope of a variable is no longer obvious in these cases. This will also impose an (hidden) order of evaluation, which is not the most desirable feature for a non-imperative language. ===== Cheers, Dimitre Novatchev. http://fxsl.sourceforge.net/ -- the home of FXSL XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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