[m-dev.] tabling, trailing and impure references

[David Overton]

On Thu, Aug 07, 2003 at 09:43:10AM +1000, David Overton wrote:
> On Mon, Aug 04, 2003 at 02:28:16PM +1000, Zoltan Somogyi wrote:
> > On 04-Aug-2003, Fergus Henderson <fjh at cs.mu.OZ.AU> wrote:
> > > > Question 2:	The reference manual says: "if you enable the use of
> > > > 		trailing ... then any use of tabling will result in a
> > > > 		"Sorry, not implemented" error at runtime."
> > > > 		
> > > > 		I get no such error from the above example in grade
> > > > 		asm_fast.gc.tr.  Does this mean the reference manual is
> > > > 		out of date, or have I just been lucky?
> > > 
> > > I think that only applies to minimal model (and/or model_non) tabling.
> > 
> > That is correct.
> > 
> > > I think the reference manual may be incorrect and/or out of date.
> > 
> > It is ambiguous. The ambiguity is supposed to be resolved by the previous
> > several paragraphs all being about minimal model tabling. Since that seems
> > not to be sufficient, I will reword that paragraph.
> 
> Thanks.  However, the part of that sentence from the reference manual
> which I left out ("... or if you select a garbage collection method
> other than the default (conservative) ...") seems to apply to
> `:- pragma memo' tabling as well.  In particular, if I compile the
> example I gave in grade asm_fast.tr I get a runtime error:
> 
> 	Mercury runtime: Cannot copy a c_pointer type
> 
> Is there any chance of getting `:- pragma memo' working in non-gc
> grades?  (We only need it for benchmarking purposes, but it would be
> useful, nonetheless, if it's possible.)

I didn't get a reply to this.  Can anyone tell me what would be involved
in getting `:- pragma memo' to work in non-gc grades, at least for
nullary functions?


David
-- 
David Overton                  Uni of Melbourne     +61 3 8344 1354
dmo at cs.mu.oz.au                Monash Uni (Clayton) +61 3 9905 5779
http://www.cs.mu.oz.au/~dmo    Mobile Phone         +61 4 0337 4393
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