Re: "distinct" predicate

[Henk Vandecasteele]

Defining the predicate as follows should do the job:


distinct(L):-
        sort(L, SortedL), %sort all elements in L and removes duplicates
        same_length(L, SortedL). % if duplicates have been removed,
                                 % length will differ, and fail.

same_length([],[]).
same_length([_|List1], [_|List2]):-
        same_length(List1, List2).



Henk


Abhinav-Bhardwaj wrote:
> hi,
> is there any way by which i can specify a rule say
> distinct..which succeeds only when all the terms in a list
> are distinct.
> for eg:
> ?- distinct([a, b, c, d]).
> yes
> ?- distinct([a, b, a, d]).
> no
>
> thanks in advance,
> regards,
> Abhinav
>
>
>
>
> _______________________________________________
> Users-prolog mailing list
> address@hidden
> http://mail.gnu.org/mailman/listinfo/users-prolog