%% Equality predicate

% Schema
%-------
database({t(integer, integer, integer),
	  t1(integer, integer)
	}).

%Derivated predicates and rules
%------------------------------
sums(X) <- t(X,Y,Z), X = Y + Z.

export sums(X).
export sums($X).

%this query will fail at compiling time
%sums1(Y) <- t1(X, Z), X = Y*Y + Z.

sums2(Y) <- t1(X, Z), Y = X + Z.

export sums2(X).
export sums2($X).