Re: 'once' predicate..

[Henk Vandecasteele]

Dear,

once/1 should behave identical as with the definition:

once(Goal):- call(Goal), !.

or identical

once(Goal):- call(Goal) -> true.

Of course the compiler can optimise the call to once/1 to avoid the
metacall.

You can use the once/1 predicate when you are only interested in the
first solution of a call to a predicate. And thus avoid unnecesary
backtracking.

Regards,

Henk


Abhinav-Bhardwaj wrote:
> hi,
> can anybody explain what is 'once' predicate, and where it is
> most commonly applied ?
> thanks and regards,
> Abhinav
>
>
>
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