[mercury-users] accumulator introduction

[David Overton]

On Fri, Jun 23, 2000 at 01:11:05PM +1000, Michael Day wrote:
> 
> Is there any way for Mercury to automatically convert this predicate to
> use an accumulator, or is it condemned to overflow the detstack forever?
> 
> sum(Input, Output) :-
>     ( if Input = 0 then
>         Output = Input
>     else
>         sum(Input-1, Output0),
>         Output = Output0 + Input
>     ).
> 
> Adding an accumulator manually to make it tail recursive gives performance
> quite close to a C loop:
> 
> for (i = 0; i <= Input; ++i) sum += i;
> 
> which is rather nice. But it would be nicer if it added the accumulator
> itself. Is this possible?
> 

Have a look at the paper:

@InProceedings{ROS1999,
  author        = "Peter Ross and David Overton and Zoltan Somogyi",
  title         = "Making Mercury Programs Tail Recursive",
  booktitle     = "Proceedings of the 9th International Workshop on
		Logic-based Program Synthesis and Transformation (LOPSTR'99)",
  year          = 1999,
  month         = sep,
  address       = "Venice, Italy",
}

available from
	http://www.cs.mu.oz.au/research/mercury/information/papers.html
.

Pete, what's the current status of this in the compiler?


David
-- 
David Overton      Department of Computer Science & Software Engineering
PhD Student        The University of Melbourne, Victoria 3010, Australia
+61 3 8344 9159    http://www.cs.mu.oz.au/~dmo
--------------------------------------------------------------------------
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
--------------------------------------------------------------------------