Hamming Numbers in prolog

Basic testing weather a number is hamming is straightforward. It can be something like this:

hamming(X) :- X =< 0, !, fail.
hamming(X) :-0 =:= (X mod 2), !, Y is X // 2,  hamming(Y).
hamming(X) :-0 =:= (X mod 3), !, Y is X // 3,  hamming(Y).
hamming(X) :-0 =:= (X mod 5), !, Y is X // 5,  hamming(Y).

But if want to make an ordered list of of all hamming numbers using lazy algorithm, we should try harder.

See this nice site that compares functional and logical languages for a solution.

His solution uses dif predicate to make the evaluation lazy. There are also other predicates for co-routines in Prolog, like freeze.

Prolog’s  freeze/frozen are similar to scheme’s promise/force.


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