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All the Perl that's Practical to Extract and Report

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  • by mauzo (8185) on 2009.06.05 8:55 (#68959)

    Still, I don't think that quite solves the problem if you assert a fact and your query fails, you probably want to retract that fact.

    This feels to me like you want an 'alternative futures' model of time: that is, when you backtrack, you not only go back to a previous 'time' but also arrange things so that when you go 'forward' again you are moving forward on a different timeline that diverges from the first at the point the backtrack went back to. If you change something and don't backtrack, subsequent computations stay on the same timeline so they keep any changes that were made.

    Of course, this means that you end up storing every state that has been present in every hypothetical timeline your program has visited, which may be a problem. If there's no way to retrieve values from 'other' timelines, you could garbage-collect them at the point they become inaccessible.