[m-dev.] Introduce !! rather than ^elem() for indexing

[Ralph Becket]

Ralph Becket, Wednesday, 10 October 2001:
> From: Ralph Becket <rafe at cs.mu.OZ.AU>
> To: mercury-developers at cs.mu.OZ.AU
> Subject: Re: [m-dev.] Introduce !! rather than ^elem() for indexing
> Organization: Mercury group, Melbourne University
> Reply-To: mercury-developers at cs.mu.OZ.AU
> 
> Michael Day, Wednesday, 10 October 2001:
> > > `A !! I' is syntactically more economical than the current Mercury
> > > convention of using `A ^ elem(I)'.  However, to make substitution of
> > > the form `A !! I := X' parse would require some work.
> > 
> > If you can have A !! I, why not have A ^ I ? Is the !! operator going to
> > be specific to lists/arrays/maps and basically replace elem?
> 
> No, I think the field access syntax is good (although I have moaned
> in the past about the parameter ordering after desugaring...)
> 
> I suppose A ^ I could work if one were prepared to allow overloading
> of higher order application.  While I haven't thought it through,
> that idea does set alarm bells ringing: it's reminiscient of the
> time I watched someone debug C++ code in which the benighted original
> author had seen fit to overload cast to void*.
> 
> - Ralph
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