[m-dev.] Feature request via Google+

[Paul Bone]

On Google+ an entity named JekejekeLogicProgramming asked the following.

    Dear All,

    I am just reading:
    http://www.mercurylang.org/information/doc-latest/mercury_ref/Trailing.html#Trailing

    Is there a Prolog API for the trailing. So that I can use functional
    trailing  from within Prolog without much C programming. I only need to be
    able to install a Prolog goal which is called once when the trail does an
    undo.

    Best Regards

I asked him to confirm what he meant by Prolog, he meant Mercury.

It should be possible to make this accessible through Mercury, provided that
trail predicates are either allowed to be impure, or take an io state pair.
Registering such predicates should have similar rules, which won't be
onerous as the programmer will already need the io state or impurity for
trailing to make sense at all.

Is anyone aware of any problems with this?

Thanks.


-- 
Paul Bone
http://www.bone.id.au