Re: [Sml-implementers] Structure sharing and type abbreviations

[Andreas R. <ros...@ps...>]

Dave Berry wrote:
> 
> Should we also consider supporting "where structure..."? And perhaps
> removing the "and" derived form of "where type...", which I believe is
> ambiguous.

It is not ambiguous, only tedious to parse. As it stands this part of
the grammar is LALR(2) but a bunch of ugly transformations can turn it
into LALR(1). Of course, it is pretty useless anyway.

Regarding "where" for structures: I second it would be great if all
implementations supported it (together with a derived form for
definitional structure specifications) since that would allow getting
rid of sharing constraints in programs altogether. IMHO this would be
preferable to relying on a relaxed structure sharing semantics.

Still I think adopting the proposal is a good idea. I would also opt for
variation 2 since I do not see any application for such obfuscated uses
of sharing (but maybe I'm just not imaginative enough...)

BTW, another old issue that definitely ought to be fixed by all
implementations: allow the "datatype ... withtype" derived form in
signatures...

	- Andreas

-- 
Andreas Rossberg, ros...@ps...

"Computer games don't affect kids; I mean if Pac Man affected us
 as kids, we would all be running around in darkened rooms, munching
 magic pills, and listening to repetitive electronic music."
 - Kristian Wilson, Nintendo Inc.