Re: Refactor of ixml grammar

Oh, er, ah.  I am always uncomfortable when there is no explicit
specification whose meaning is the default behavior.  

(An early influence on me, I guess, was an article by Harlan Mills of
IBM on how to use System 360 JCL with fewer errors; the basic idea
was that many errors were caused by the complicated system of
defaults, which changed depending on various partial specifications.
His remedy:  write JCL as if it had no default values.  That way, you
never needed to learn the rules for defaults.  I do still do that when
learning new languages; it helps.  I also decline to learn more than 
one or two levels of operator priorities.)

Michael 


> On 4,Nov2021, at 4:34 AM, Steven Pemberton <steven.pemberton@cwi.nl> wrote:
> 
> Another change I think worth making:
> A tmark is either ^ and -, since @ is completely meaningless for terminals.
> 
> However, ^ also has no use, since that is the default anyway, and there is no usecase where you need it to override anything. 
> So I propose making:
> 
> 	@tmark: "-".
> 
> Steven
> 
> On Thursday 04 November 2021 00:02:54 (+01:00), Steven Pemberton wrote:
> 
> > In an idle moment, I refactored the grammar. Comments gladly received.
> > Changes: * I hid all nonessential terminals. I know above all Tom was asking for this.
> > * I moved the spaces from the rule for ixml into the rule for rule. Tidier and more consistent.
> > * I renamed S to s.
> > * I simplified 'namestart', since I realised class L covered all the cases.
> >
> > I think that's all.
> >
> > See attachment.
> >
> > Steven
>

Received on Thursday, 4 November 2021 14:15:39 UTC