lambda - Compute Dot Product of Two Vectors -

i'm supposed create predicate in prolog such iprod(list1, list2, result) takes 2 lists of equal length , each contain integers. result dot product of 2 vectors.

for example, list1 = [1,2,3], list2 = [4,5,6], result 1*4 + 2*5 + 3*6. i'm not supposed use built-in dotproduct function.

my code far:

iprod([],[], 0). iprod([h1|list1], [h2|list2], result h1 * h2) :- iprod(list1, list2, result). 

in visual prolog:

domains   ilist=integer*  predicates   iprod(ilist, ilist, integer, integer)  clauses   iprod([], _, r, r).       iprod([x|xs], [y|ys], a, r):-     m = x * y,     rnew = + m,     iprod(xs, ys, rnew, r).   goal   iprod([1,2,3],[4,5,6], 0, r). 

results in 32. sorry, no other prolog implementation available @ hand.