Re: [Caml-list] Recursive lists

[Keith Wansbrough <Keith.Wansbrough@cl.cam.ac.uk>]

Alex Baretta wrote:
> David Brown wrote:
> > On Fri, Oct 08, 2004 at 04:42:44PM +0200, Alex Baretta wrote:
> > 
> >>Keith Wansbrough wrote:
> > 
> > I doubt that most users of list operations want the extra overhead needed
> > to check for cycles.  Recursive lists are fairly rare in strict languages.

Please be careful with your attributions.  I did not write this
comment; David Brown did.  I do entirely agree, though.  And I
reiterate my earlier point - if you have an algorithm that uses a
potentially-cyclic datastructure and depends on detecting cycles, you
should build in some cycle-detection into the datastructure.  You
should not depend on fragile and underspecified operations like
pointer equality.

Alex, I didn't understand your earlier point about needing to compare
*tails* of visited nodes - why is just comparing nodes not sufficient?
Surely if two nodes compare physically equal, their tails must also be
equal.

--KW 8-)

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