Re: [q-lang-users] Q 7.2 RC1 Issue 2: Notation

[Albert G. <Dr....@t-...>]

John Cowan wrote:
> I'm not happy with "over" as the notation for rational numbers.
> In particular, "1 over 5+2 over 3" looks totally wrong for 1/5 + 2/3;
> the visual grouping is hopelessly broken.  I realize that we can't use
> "/" for this purpose, but can't we use another symbol operator?

Actually I've been tossing around the idea to make the "/" builtin 
undefined on Int Int so that it could be defined in the library. But 
that would probably break just about any Q script out there, so it's not 
really an option.

> 
> I would propose "|", which is visually close to "/" and is used in the
> "units" program for the same purpose.  A non-ASCII alternative would be ÷
> (division sign).  These would be very minor changes to the lexer.

"|" is not possible as it is already used as a delimiter in 
list/stream/tuple notation, so we'd get very evil ambiguities in the 
expression grammar. And I don't like the idea of using something which 
is not 7 bit ASCII. Of course a programmer can easily define his own 
aliases using extended characters, but the language and the library 
should be 7 bit only IMHO.

So I'm afraid that the only 7 bit ASCII punctuation symbol that's left 
is "%" (incidentally, this is also what Haskell uses for the same 
purpose). It's been a while since this has been used as a comment 
character, so I'd say it's safe to reuse it now. Then you could type 
your example as "1%5 + 2%3". Acceptable?

ATM user-defined operator symbols can only be made from punctuation 
symbols outside the 7 bit range, but I guess that I could change that, 
even if it's only to be used in this single case.

Rob, what's your take on this? Do you prefer "over" or "%"? After all 
it's your module. ;-)

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikinformatik.uni-mainz.de/ag