Re: Bracket heresies. What about subscripting?

[Jim Blandy <jimb@red-bean.com>]

> > This is terrible, disgusting chaos, a horrible perversion of the
> > Scheme way
> 
> Well, thank you for your being straight to the point.  :)

Actually, I was joking.  That's why I went on to indicate another
possible application --- it wasn't sarcasm.  I don't think it's so
horrible.  Sorry I wasn't clearer.

> But what is the chaos part?  (m i j), the setter style, or objects
> being operators in general?

The latter.

> Below I'm going to argue a little for this style, but first I want to
> stress that this syntax was chosen mainly to get a user interface
> which could compete with Matlab in easy of use.  I'm not saying that
> this is how subscripting should work in general in Scheme.  It's just
> that when you work with numerical algorithms the code becomes so
> obscure if formulas consists of things like
> (* (vector-ref (vector-ref A i) j) (vector-ref (vector-ref B j) k)).

I've noticed this, too.  String handling is a mess, too.  What can we
do to improve this, without jeopardizing our opportunities for future
optimization?

> You must agree that it is natural to regard a matrix as an operator.
> (This is how matrices are regarded in linear algebra.)
> 
>   (M V1) --> V2  (where V1 and V2 are vectors)
> 
> Right?  

Yes.


> > Now, wouldn't it be cool if applying a regexp to a string
> > returned a list of the substrings?
> > 
> > ((make-regexp "(.*)/([^/]*)") "/usr/local/bin/gcc")
> > => ("/usr/local/bin" "gcc")
> > 
> > (define (x-display-hostname display)
> >   (car ((make-regexp "([^:]*):.*") display)))
> 
> I guess the problem is that with objects being operators you could
> easily end up with unreadable code.  Note that our application
> specific matrix syntax was intended to enhance readability of code
> (* (A i j) (B j k)).

I don't find the stringy syntax unreadable, though.  The idea is that
a regexp is a function which breaks its argument into pieces.  I
couldn't think of anything more natural for a regexp to do.  I guess
you didn't like it.  *sigh*