root/trunk/examples/metapredicates/predicates.lgt

% some simple predicates to use with library meta-predicates (e.g. fold_left/4
% and partition/4) compiled as plain Prolog code and thus defined in the "user"
% pseudo-object:

sum_squares(X, Y, Z) :-
    Z is X*X + Y*Y.


even_integer(I) :-
    I mod 2 =:= 0.


% a simple object defining some predciates to use with library meta-predicates:

:- object(predicates).

    :- info([
        version is 1.0,
        date is 2008/11/19,
        author is 'Paul Crocker',
        comment is 'Some predicates for testing the library meta-predicates.']).

    :- public(tuple/3).

    tuple((X1, Y1), (X2, Y2), (X, Y)) :-
        X is X1 + X2,
        Y is Y1 + Y2.

    :- public(sum/3).

    sum(X, Y, Z) :-
        Z is X + Y.

    :- public(product/3).

    product(X, Y, Z) :-
        Z is X * Y.

:- end_object.