From: "John W. Kennedy" <jwkenne@...>
Date: 2004-10-02T13:59:58+09:00
Subject: Re: consider "..." as ellipsis (Re: Range syntax theory)

Bob Sidebotham wrote:
> The reference language used ":" 
> for ranges, but, if I remember correctly, the implementation I used 
> allowed ".." as a synonym, just in case you couldn't type ":" on your 
> favourite key punch equipment...

You are correct, sir!

> So, I disagree: I think that ".." came from trying to represent ":" in 
> ancient software/hardware environments. Why ":" was used by languages 
> like Algol, in the first place, I have no idea.

Algol paid no attention to technical restrictions at all. It had left 
and right quotes, for example, and assumed availability of lower case 
letters in two different alphabets.  (ALGOL keywords were represented in 
bold. This wasn't just a publishing convention; the language didn't have 
reserved words, but, unlike FORTRAN and PL/I, did not have syntax rules 
that allowed keywords to be distinguished from variable names, so the 
bold distinction was syntactically necessary.)  Practical ALGOL, 
therefore, was a hideous mess that looked something like this:

'PROCEDURE' SUM10.,
   'INTEGER' I, T.,
'BEGIN'
     T .= 0.,
     'FOR' I .= 1 'STEP' 1 'TO' 10 'DO'
         T .= T + I.,
     OUTSTRING (1, '('THE SUM OF INTEGERS 1 TO 10 IS ')').,
     OUTINTEGER (1, I)
'END'

Some systems that relied heavily on ALGOL used more attractive 
representations, but at the cost of no longer being isomorphic to 
standard ALGOL.

-- 
John W. Kennedy
"The poor have sometimes objected to being governed badly; the rich have 
always objected to being governed at all."
   -- G. K. Chesterton.  "The Man Who Was Thursday"