Hi, in installing 1002 error Thomas answered: .. you cannot have two instances of Vip 9 or two instances of Vip10. Actually Visual Prolog itself doesn't mind you can have as many as you like, but when making installers you will have to decide which is the same and should be considered updates and wh...

Hi Paul, all predicates of your old code are still there in VIP 10ce. I have tried it, created a new console project in VIP 10ce and put the code with a little add-on in main.pro : class globals properties desired_Output : real. end class globals implement globals class facts desired_Output : real :...

Hi Kim, working with integers is same easy as with strings. Here are two working variants of your code which may hopefully help: clauses run() :- StrList = ["Huey", "Dewey", "Louie"], processStrList(StrList, 1). class predicates processStrList : (string* DataList, integ...

OK. But just to the objSetM_chain construction: Of course a persistent data structure is one where every operation returns a new data structure but also preserves the old one. I think, you mention it because I made a mistake: My objSetM_chain example is not appropriate. When I tried to make class ob...

Hello Thomas,

on attached example the compiler throws "The expression has type 'arrayP::repDomain', which is incompatible with the type 'arrayP::repDomain{@ItemType}'". Is it a bug?

Thank you again for the detailed answer. If I had to pay you for all the time, you have invested over the years in answering my posts, I would be a poor man. I understand that the proposed construction is a hook into the runtime system rather than a genuine language feature and the if-rewrite you pr...

Thank you, Thomas !

In old VIP 7.3 dialogs have been looking different, but fonts have also been selectable:

Hello Linda, it looks like something is messed up with the fonts on your PC. Maybe the font, which VIP uses in the editor, is missing. Under "Tools", "Options..." it is possible to specify font for all IDE windows. I suppose my font settings are default: Options.jpg Try to change...

I have been seeking for a way which solves the problem, but does not produce too much effort to implement. Can this one win your sympathy? Please check: In backtrack points VIP is pushing some data on the stack. Let me call that data a backtrack-frame. Add one extra pointer to the backtrack-frame. T...

Without adding "amortized", the performance claim is not correct. Because, when placing the undo calls right behind the regular backtrack points, a single failure can trigger many undo calls. Thus the backtracking initiated by a single failure executes in O(n) in the persistent array const...

To be exact about the performance characteristics of the persistent array construction compared to the ephemeral arrayM : The characteristics are preserved in amortized costs. The cost to move n states forwards is in O(n), the cost to move backwards n states is also in O(n). Thus amortized, every si...

I have a class named stateManager in which the undo functionality is also not tied to backtracking (see attached Example2.zip). Both classes reversion and stateManager are about turning an ephemeral data structure into a persistent data structure . The reversion class only supports accessing the new...

Add-on: The example can be simplified. When using the reversion class, the stack fact is not needed: class facts state : string := "initial". class predicates changeState : (string Update). clauses changeState(Update) :- State = state, state := Update, reversion::addUndoAction({ :- state :...

Thank you Thomas for the info! To treat the problem I am using a class named reversion (see it in attached Example.zip). Using that class the example looks like: class facts state : string := "initial". class facts stack : string* := []. class predicates changeState : (string Update). clau...