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Date:Mon May 14 08:55:33 2001 
Subject:Re: Syntactic vs semantic extensions (reply part "b") 
From:Jonathan L Cunningham 
Volume-ID:1010514.02 

On 11 May 2001 12:14:35 GMT, kers@hplb.hpl.hp.com () wrote:

>In article <9dghbi$csm$1@soapbox.cs.bham.ac.uk>,
>	Aaron.Sloman.XX@cs.bham.ac.uk (Aaron Sloman See text for reply address) writes:
>> [To reply replace "Aaron.Sloman.XX" with "A.Sloman"]
(snip)
>> (b) [For information only] Pop-11 already has mechanisms for dealing
>> with two types of representations for characters.
>> 
>>     1. There's the standard ASCII representation as an 8-bit integer
>>     2. There are also "display strings", which are used in Ved/Xved
>
>While I appreciate the intentions of, and the work that's gone into, 
>the dstring type, I'm not convinced that it's the right approach. For
>example, it doesn't generalise to multiple-font lines. However, in the
>absence of any (on my part!) practical experience, I can only report
>misgivings and not attempts-in-progress.

I assumed the dstrings were intended to cope with Unicode characters
(16 bit entities). The top byte of attributes is a bit of a hack, but
at least there is space for the full 16 bit codes.

I'm inclined to agree about other text attributes. Nowadays, you
really need to be able to encode font colour (typically up to 24
bits of data) font size (another 8 bits??), font style, (5 bits?
6 bits?), font family etc.

I think the attributes byte is really just a hack for use in Ved.

It should *not* have been used in documentation files.

Nowadays there is a clear standard for markup, based on SGML.

Yes, you've heard of it: HTML :-).

It's not perfect, by any means, but something based on XML is going
to end up incompatible with the rest of the world, unless it can
be sold (in the concept not financial sense) to the rest of the world.

Meanwhile, HTML will be around for a good few years yet.

Has anyone got any code for reading in a file of HTML and displaying
it in a VED buffer on a "best efforts" basis? (Did I already ask this
on popforum, if so, I apologise for forgetting the answer.) Why
would anyone want to? Because there would be advantages in looking
at TEACH and REF files from inside VED, and there are even more
obvious advantages for all the TEACH and REF files to be converted
to HTML. (Wouldn't you just love to be able to include diagrams
in the TEACH files?)

(snip)
><hobbyhorse>
>My experience with Pepper has convinced me that allowing arbitrary
>procedures to be called both postfix (as in Pop's X.F) and indeed
>infix (as in object-classy X.F(A) and in Pepper's X @F A) is a
>significant syntactic improvement to a language.
></hobbyhorse>
>
>(Extensive list of semantically wonderful stuff deleted)
>
>> By comparison with "semantic" extensions of the above types, I believe
>> changes to the syntax of existing constructs are really of marginal
>> importance!
>
>Not for beginners, or people you're trying to seduce to the Way, or
>when you're trying to eliminate the nasty little code production burrs.

My feeling on this was given in my other (part "a") reply -- I think
Chris is right. And otherwise these little niggles are like an
itch you can't scratch. If the language is frozen, it will die.

Of course, that doesn't mean we'd agree on what syntax changes should
be made!

Jonathan

-- 
Jonathan L Cunningham