[mercury-users] Indexing & operational semantics

[Peter Schachte]

On Wed, Feb 02, 2000 at 12:24:06PM +1300, Richard A. O'Keefe wrote:
> Peter Schachte wrote:
> 	(I'm using && as sequential conjunction for this
> 	example.)  The only subtlety is in choosing the precedence for &&.
> 	Should a, b && c, d associate as (a,b) && (c,d) or as a, (b && c), d?
> 	
> Either way is bound to confuse someone.

It's a danger, but I think it manageable.  It's much like `,' and `;'
now:  the solution is good layout conventions.  If I write, eg,

	a,
	(   b
	&&  c
	),
	d.

or
	(   a,
	    b
	&&  c,
	    d
	).

the meaning is pretty clear.  I guess now I'm arguing for making `,'
bind tighter than `&&'; it just seems to work out better that way.

>  I think the answer is to borrow
> an idea from Ada, and say that any given conjunction may contain all
> `commutative and's or all `sequential and's, but it's a syntax error to
> mix them.

That seems a bit extreme.


-- 
Peter Schachte                     How does a project get to be a year late?
mailto:schachte at cs.mu.OZ.AU        ... One day at a time. -- Frederick
http://www.cs.mu.oz.au/~schachte/  Brooks, _The Mythical Man Month_ 
PGP: finger schachte at 128.250.37.3  
--------------------------------------------------------------------------
mercury-users mailing list
post:  mercury-users at cs.mu.oz.au
administrative address: owner-mercury-users at cs.mu.oz.au
unsubscribe: Address: mercury-users-request at cs.mu.oz.au Message: unsubscribe
subscribe:   Address: mercury-users-request at cs.mu.oz.au Message: subscribe
--------------------------------------------------------------------------