Re: [eclipse-clp-users] ECLiPSe puzzle problem doesn't work for me.

On 30/09/2013 15:14, Paul Cannongeyser wrote:
> I coded the Who with whom puzzle problem shown in section 3.6 entitled Who with whom? -
> propagation, page 120, of AN_CLP.pdf (i.e., the book entitled "A Quick and Gentle Guide to
> Constraint Logic Programming via ECLiPSe" by Antoni Niederlinski) from http://www.anclp.pl/.
>
> :- lib(ic).
>
> top:-
> [Andy,Ben,Carl,Dusty]::[1,4],
> [Olive,Eva,Paula,Sabina]::[1,4],

These two lines are wrong, they should read

[Andy,Ben,Carl,Dusty]::1..4,
[Olive,Eva,Paula,Sabina]::1..4,

i.e. the variable domains do not consist of the two values 1 and 4,
but of the four values in the range 1..4.


> ...
> write(Olive),write(" "),write(Eva),write(" "),
> write(Paula),write(" "),write(Sabina).
>
> I type "top" into the Query Entry text field, hit Enter, and observe the following in the Results
> section.
>
> ?- top.
> No (0.00s cpu)
>
> I am new to ECLiPSe.  I don't understand why at least the write statements at the end of the
> program don't print anything.

You can read the comma between your constraints as a "sequential AND"
operator, similar to && in languages like C or Java.  That means,
as soon as one constraint is false (in this case Paula#=2),
anything to the right of this constraint is not executed anymore.

-- Joachim